OneFS and Cluster Quorum

Received a couple of recent enquires about the role and effects of cluster quorum in OneFS. So thought it might be useful to revisit this, and associated concepts, in an article.

The premise was this:

A 3 node cluster at +2d:1n or +1n protection can run fine in a degraded mode with only two active nodes and one failed node:

Given the above, shouldn’t a 4 node cluster at +2n also be able to sustain a two node failure and run fine in degraded state with two active nodes?

Spoiler alert: The answer is no, and the reason is the OneFS cluster quorum requirement.

So what’s going on here?

In order for a cluster to properly function and accept data writes, a quorum of nodes must be active and responding. A quorum is defined as a simple majority: a cluster with N nodes must have ⌊N/2⌋+1 nodes online in order to allow writes. For example, in a seven-node cluster, four nodes would be required for a quorum. If a node or group of nodes is up and responsive, but is not a member of a quorum, it runs in a read-only state.

OneFS uses a quorum to prevent ‘split-brain’ conditions that can be introduced if the cluster should temporarily divide into two clusters. By following the quorum rule, the architecture guarantees that regardless of how many nodes fail or come back online, if a write takes place, it can be made consistent with any previous writes that have ever taken place. The quorum also dictates the number of nodes required in order to move to a given data protection level. For an erasure-code-based protection-level of 𝑁+𝑀, the cluster must contain at least 2𝑀+1 nodes. For example, a minimum of five nodes is required for a +2n configuration:

This allows for a simultaneous loss of two nodes while still maintaining a quorum of three nodes for the cluster to remain fully operational.

If a cluster does drop below quorum, the file system will automatically be placed into a protected, read-only state, denying writes, but still allowing read access to the available data.

Within OneFS, quorum is a property of the group management protocol (GMP) group which helps enforce consistency across node disconnects. It is very similar to the common definition of quorum in distributed systems. It can be shown that requiring ⌊𝑁/2⌋+ 1 replicas to be available can guarantee that no updates are lost. Quorum performs this specific purpose within OneFS.

Since both nodes and drives in OneFS may be readable, but not writable, OneFS actually has two quorum properties:

Type Description
Read quorum Read quorum is defined as having ⌊𝑁/2⌋ + 1 nodes readable.
Write quorum Write quorum is defined as having at least ⌊𝑁/2⌋ + 1 nodes writable.

Under the hood, OneFS read quorum is represented by the sysctl ‘efs.gmp.has_quorum’, and write quorum by  ‘efs.gmp.has_super_block_quorum’. For example:

# sysctl efs.gmp.has_quorum

efs.gmp.has_quorum: 1

# sysctl efs.gmp.has_super_block_quorum

efs.gmp.has_super_block_quorum: 1

In the above example, the value of ‘1’ for each confirms that the cluster currently has both read and write quorum respectively.

Note that any nodes that are not in a cluster’s main quorum group form multiple groups. A group of nodes with quorum is referred to as the ‘majority side’. Similarly, any node group without quorum is termed a ‘minority side’. By definition, there can only be one majority group, but there may be multiple minority groups. A group which has one or more components in a failed state is called ‘degraded’. The degraded property is frequently used as an optimization to avoid checking the capabilities of each component. The term ‘degraded’ is also used to refer to components without their maximum capabilities.

For example, consider the earlier 4-node cluster example with a protection level of +2n and two nodes down. Even though the protection level can theoretically sustain two node failures, the minimum cluster size has been violated, hence the cluster cannot write due to lack of quorum. The following table lists various OneFS protection levels and their associated minimum cluster or pool sizes and quorum counts:

FEC Protection level Failure Tolerance Minimum Cluster/Pool Size Minimum Quorum Size
+1 Tolerate failure of 1 drive OR 1 node 3 nodes 2 nodes
+2 Tolerate failure of 2 drives OR 2 nodes 5 nodes 3 nodes
+3 Tolerate failure of 3 drives or 3 nodes 7 nodes 4 nodes
+4 Tolerate failure of 4 nodes 9 nodes 5 nodes

The OneFS Job Engine also includes a process called Collect, which acts as an orphaned block collector. If a cluster splits during a write operation, some blocks that were allocated for the file may need to be re-allocated on the quorum side. This will ‘orphan’ allocated blocks on the non-quorum side. When the cluster re-merges, the job engine’s Collect job locates these orphaned blocks through a parallelized mark-and-sweep scan and reclaims them as free space for the cluster.

File system operations typically query a GMP group several times before completing. A group may change over the course of an operation, but the operation needs a consistent view. This is provided by the group info, which is the primary interface modules use to query group state.

The efs.gmp.group sysctl can be queried to determine the current group state of a cluster. For example:

# sysctl efs.gmp.group

efs.gmp.group: <8f8f4b> (92) :{ 1-14:0-14, 15:0-13, 16-19:0-14, 20:0-13, 21-33:0-14, 34:0-4,6-10,12-14, 35-36:0-14, 37-48:0-19, 49-60:0-14, 61-62:0-13, 63-81:0-14, 82:0-7,9-14, 83-87:0-14, 88:0-13, 89-91:0-14, 92:0-1,3-14, smb: 1-92, nfs: 1-92, swift: 1-92, all_enabled_protocols: 1-92, isi_cbind_d: 1-92, lsass: 1-92, s3: 1-92, external_connectivity: 1-92 }

As shown in this large cluster example above, the output includes the GMP’s group state, but also information about services provided by nodes in the cluster. This allows nodes in the cluster to discover when services change state on other nodes and take the appropriate action when this happens. An example is SMB lock expiry, which uses GMP service information to clean up locks held by other nodes when the service owning the lock goes down.

Additional detailed current GMP state information can be gleaned from the output of the following sysctl:

# sysctl efs.gmp.current_info

Processes change the service state in GMP by opening and closing service devices. A particular service will transition from down to up in the GMP group when it opens the file descriptor for a device. Closing the service file descriptor will trigger a group change that reports the service as down. A process can explicitly close the file descriptor if it chooses, but most often the file descriptor will remain open for the duration of the process and closed automatically by the kernel when it terminates.

OneFS depends on a consistent view of a cluster’s group state. For example, in addition to read and write quorum, other decisions, such as choosing lock coordinators, are made assuming all nodes have the same coherent notion of the cluster.

As such, an understanding of OneFS quorum, groups, and their related group change messages allows you to determine the current health of a cluster – as well as reconstruct the cluster’s history when troubleshooting issues that involve cluster stability, network health, and data integrity.

Group changes originate from multiple sources, depending on the particular state. Drive group changes are initiated by the drv module. Service group changes are initiated by processes opening and closing service devices. Each group change creates a new group ID, comprising a node ID and a group serial number. This group ID can be used to quickly determine whether a cluster’s group has changed, and is invaluable for troubleshooting cluster issues, by identifying the history of group changes across the nodes’ log files.

GMP provides coherent cluster state transitions using a process similar to two-phase commit, with the up and down states for nodes being directly managed by the GMP. The Remote Block Manager (RBM)  provides the communication channel that connect devices in the OneFS. When a node mounts /ifs it initializes the RBM in order to connect to the other nodes in the cluster, and uses it to exchange GMP Info, negotiate locks, and access data on the other nodes.

Before /ifs is mounted, a ‘cluster’ is just a list of MAC and IP addresses in array.xml, managed by ibootd when nodes join or leave the cluster. When mount_efs is called, it must first determine what it‘s contributing to the file system, based on the information in drives.xml. After a cluster (re)boot, the first node to mount /ifs is immediately placed into a group on its own, with all other nodes marked down. As the Remote Block Manager (RBM) forms connections, the GMP merges the connected nodes, enlarging the group until the full cluster is represented. Group transactions where nodes transition to UP are called a ‘merge’, whereas a node transitioning to down is called a split.

OneFS Software-Defined Persistent Memory Journal

Unlike previous platforms which used NVDIMMs, the F710 and F210 nodes see a change to the system journal, instead using a 32GB Software Defined Persistent Memory (SDPM) solution to provide persistent storage for the OneFS journal. This change also has the benefit of freeing up a DIMM slot, unlike the NVDIMM on previous platforms.

But before we get into the details, first, a quick refresher on the OneFS journal.

A primary challenge for any storage system is providing performance and ACID (atomicity, consistency, isolation, and durability) guarantees using commodity drives. Drives only support the atomicity of a single sector write, yet complex file system operations frequently update several blocks in a single transaction. For example, a rename operation must modify both the source and target directory blocks. If the system crashes or loses power during an operation that updates multiple blocks, the file system will be inconsistent if some updates are visible and some are not.

The journal is among the most critical components of a PowerScale node. When the OneFS writes to a drive, the data goes straight to the journal, allowing for a fast reply.

OneFS uses journalling to ensure consistency across both disks locally within a node and disks across nodes.

Block writes go to the journal first, and a transaction must be marked as ‘committed’ in the journal before returning success to the file system operation. Once the transaction is committed, the change is guaranteed to be stable. If the node crashes or loses power, the changes can still be applied from the journal at mount time via a ‘replay’ process. The journal uses a battery-backed persistent storage medium, such as NVRAM, in order to be available after a catastrophic node event such as a crash or power loss. It must also be:

Journal Performance Characteristic Description
High throughput All blocks (and therefore all data) go through the journal, so it cannot become a bottleneck.
Low latency Since transaction state changes are often in the latency path multiple times for a single operation, particularly for distributed transactions.

The OneFS journal mostly operates at the physical level, storing changes to physical blocks on the local node. This is necessary because all initiators in OneFS have a physical view of the file system, and therefore issue physical read and write requests to remote nodes. The OneFS journal supports both 512byte and 8KiB block sizes of 512 bytes for storing written inodes and blocks respectively.

By design, the contents of a node’s journal are only needed in a catastrophe, such as when memory state is lost. For fast access during normal operation, the journal is mirrored in RAM. Thus, any reads come from RAM and the physical journal itself is write-only in normal operation. The journal contents are read at mount time for replay. In addition to providing fast stable writes, the journal also improves performance by serving as a write-back cache for disks. When a transaction is committed, the blocks are not immediately written to disk. Instead, it is delayed until the space is needed. This allows the I/O scheduler to perform write optimizations such as reordering and clustering blocks. This also allows some writes to be elided when another write to the same block occurs quickly, or the write is otherwise unnecessary, such as when the block is freed.

So the OneFS journal provides the initial stable storage for all writes and does not release a block until it is guaranteed to be stable on a drive. This process involves multiple steps and spans both the file system and operating system. The high-level flow is as follows:

Step Operation Description
1 Transaction prep A block is written on a transaction, for example a write_block message is received by a node. An asynchronous write is started to the journal. The transaction prepare step will wait until all writes on the transaction complete.
2 Journal delayed write The transaction is committed. Now the journal issues a delayed write. This simply marks the buffer as dirty.
3 Buffer monitoring A daemon monitors the number of dirty buffers and issues the write to the drive upon reach its threshold.
4 Write completion notification The journal receives an upcall indicating that the write is complete.
5 Threshold reached Once journal space runs low or an idle timeout expires, the journal issues a cache flush to the drive to ensure the write is stable.
6 Flush to disk When cache flush completes, all writes completed before the cache flush are known stable. The journal frees the space.

The F710 and F210 see the introduction of Dell’s VOSS M.2 SSD drive as the non-volatile device for the SDPM journal vault.  The SDPM itself comprises two main elements:

Component Description
BBU The BBU pack (battery backup unit) supplies temporary power to the CPUs and memory allowing them to perform a backup in the event of a power loss.
Vault A 32GB M.2 NVMe to which the system memory is vaulted.

While the BBU is self-contained, the M.2 NVMe vault is housed within a VOSS module, and both components are easily replaced if necessary.

The following CLI command confirms the 32GB size of the SDPM journal in the F710 and F210 nodes:

# grep -r supported_size /etc/psi/psf

/etc/psi/psf/MODEL_F210/journal/JOURNAL_SDPM/journal-1.0-psi.conf:             supported_size = 34359738368;

/etc/psi/psf/MODEL_F710/journal/JOURNAL_SDPM/journal-1.0-psi.conf:             supported_size = 34359738368;

/etc/psi/psf/journal/JOURNAL_NVDIMM_1x16GB/journal-1.0-psi.conf:               supported_size = 17179869184;

The basic SDPM operation is illustrated in the diagram below:

Essentially, the node’s memory state, including any uncommitted writes, etc, in the DDR5 RDIMMS that are being protected, come up through the memory controller, through the CPU and caching hierarchy, and are then vaulted to the non-volatile M.2 within the VOSS module.

The VOSS M.2 module itself is comprised of the following parts:

In the event of a failure, this entire carrier assembly is replaced, rather than just the M.2 itself.

Note that with the new VOSS, M.2 firmware upgrades are now managed by iDRAC using DUP, rather than by OneFS and the DSP as in prior PowerScale platforms.

Both the BBU and VOSS module are located at the front of the chassis, and are connected to the motherboard and power source as depicted by the red and blue lines in the following graphic:

Additionally, with OneFS 9.7, given the low latency IO characteristics of the drives, the PowerScale NVMe-based all-flash nodes also now have a write operation fast path direct to SSD for newly allocated blocks as shown below:

This is a major performance boost, particularly for streaming write workloads, and we’ll explore this more closely in a future article.

PowerScale F710 Platform Node

In this article, we’ll turn our focus to the new PowerScale F710 hardware node that was launched a couple of weeks back. Here’s where this new platform lives in the current hardware hierarchy:

The PowerScale F710 is a high-end all-flash platform that utilizes a dual-socket 4th gen Zeon processor with 512GB of memory and ten NVMe drives, all contained within a 1RU chassis. Thus, the F710 offers a substantial hardware evolution from previous generations, while also focusing on environmental sustainability, reducing power consumption and carbon footprint, while delivering blistering performance. This makes the F710 and ideal candidate for demanding workloads such as M&E content creation and rendering, high concurrency and low latency workloads such as chip design (EDA), high frequency trading, and all phases of generative AI workflows, etc.

An F710 cluster can comprise between 3 and 252 nodes. Inline data reduction, which incorporates compression, dedupe, and single instancing, is also included as standard to further increase the effective capacity.

The F710 is based on the 1U R660 PowerEdge server platform, with dual socket Intel Sapphire Rapids CPUs. Front-End networking options include 10/25 GbE and with 100 GbE for the Back-End network. As such, the F710’s core hardware specifications are as follows:

Attribute F710 Spec
Chassis 1RU Dell PowerEdge R660
CPU Dual socket, 24 core Intel Sapphire Rapids 6442Y @2.6GHz
Memory 512GB Dual rank DDR5 RDIMMS (16 x 32GB)
Journal 1 x 32GB SDPM
Front-end network 2 x 100GbE or 25GbE
Back-end network 2 x 100GbE
NVMe SSD drives 10

These node hardware attributes can be easily viewed from the OneFS CLI via the ‘isi_hw_status’ command. Also note that, at the current time, the F710 is only available in a 512GB memory configuration.

Starting at the business end of the node, the front panel allows the user to join an F710 to a cluster and displays the node’s name once it has successfully joined.

Removing the top cover, the internal layout of the F710 chassis is as follows:

The Dell ‘Smart Flow’ chassis is specifically designed for balanced airflow, and enhanced cooling is primarily driven by four dual-fan modules. Additionally, the redundant power supplies also contain their own air flow apparatus and can be easily replaced from the rear without opening the chassis.

For storage, each PowerScale F710 node contains ten NVMe SSDs, which are currently available in the following capacities and drive styles:

Standard drive capacity SED-FIPS drive capacity SED-non-FIPS drive capacity
3.84 TB TLC 3.84 TB TLC
7.68 TB TLC 7.68 TB TLC
15.36 TB QLC Future availability 15.36 TB QLC
30.72 TB QLC Future availability 30.72 TB QLC

Note that 15.36TB and 30.72TB SED-FIPS drive options are planned for future release.

Drive subsystem-wise, the PowerScale F710 1RU chassis is fully populated with ten NVMe SSDs. These are housed in drive bays spread across the front of the node as follows:

This is in contrast to, and provides improved density over its predecessor, the F600, which contains eight NVMe drives per node.

The NVMe drive connectivity is across PCIe lanes, and these drives use the NVMe and NVD drivers. The NVD is a block device driver that exposes an NVMe namespace like a drive and is what most OneFS operations act upon, and each NVMe drive has a /dev/nvmeX, /dev/nvmeXnsX and /dev/nvdX device entry  and the locations are displayed as ‘bays’. Details can be queried with OneFS CLI drive utilities such as ‘isi_radish’ and ‘isi_drivenum’. For example:

# isi_drivenum

Bay  0   Unit 15     Lnum 9     Active      SN:S61DNE0N702037   /dev/nvd5

Bay  1   Unit 14     Lnum 10    Active      SN:S61DNE0N702480   /dev/nvd4

Bay  2   Unit 13     Lnum 11    Active      SN:S61DNE0N702474   /dev/nvd3

Bay  3   Unit 12     Lnum 12    Active      SN:S61DNE0N702485   /dev/nvd2

Bay  4   Unit 19     Lnum 5     Active      SN:S61DNE0N702031   /dev/nvd9

Bay  5   Unit 18     Lnum 6     Active      SN:S61DNE0N702663   /dev/nvd8

Bay  6   Unit 17     Lnum 7     Active      SN:S61DNE0N702726   /dev/nvd7

Bay  7   Unit 16     Lnum 8     Active      SN:S61DNE0N702725   /dev/nvd6

Bay  8   Unit 23     Lnum 1     Active      SN:S61DNE0N702718   /dev/nvd1

Bay  9   Unit 22     Lnum 2     Active      SN:S61DNE0N702727   /dev/nvd10

Moving to the back of the chassis, the rear of the F710 contains the power supplies, network, and management interfaces, which are arranged as follows:

The F710 nodes are available in the following networking configurations, with a 25/100Gb ethernet front-end and 100Gb ethernet back-end:

Front-end NIC Back-end NIC F710 NIC Support
100GbE 100GbE Yes
100GbE 25GbE No
25GbE 100GbE Yes
25GbE 25GbE No

Note that, like the F210, an Infiniband backend is not supported on the F710 at the current time.

Compared with its F600 predecessor, the F710 sees a number of hardware performance upgrades. These include a move to PCI Gen5, Gen 4 NVMe, DDR5 memory, Sapphire Rapids CPU, and a new software-defined persistent memory file system journal ((SPDM). Also the 1GbE management port has moved to Lan-On-Motherboard (LOM), whereas the DB9 serial port is now on a RIO card. Firmware-wise, the F710 and OneFS 9.7 require a minimum of NFP 12.0.

In terms of performance, the new F710 provides a considerable leg up on both the previous generation F600 and F600 prime. This is particularly apparent with NFSv3 streaming reads, as can be seen below:

Given its additional drives (ten SSDs versus eight for the F600s) plus this performance disparity, the F710 does not currently have any other compatible node types. This means that, unlike the F210, the minimum F710 configuration requires the addition of a three node pool.

PowerScale F210 Platform Node

In this article, we’ll take a quick peek at the new PowerScale F210 hardware platform that was released last week. Here’s where this new node sits in the current hardware hierarchy:

The PowerScale F210 is an entry level, performant, all-flash platform that utilizes NVMe SSDs and a single-socket CPU 1U PowerEdge platform with 128GB of memory per node.  The ideal use cases for the F210 include high performance workflows, such as M&E, EDA, AI/ML, and other HPC applications.

An F210 cluster can comprise between 3 and 252 nodes, each of which contains four 2.5” drive bays populated with a choice of 1.92TB, 3.84TB, 7,68TB TLC, or 15.36TB QLC enterprise NVMe SSDs. Inline data reduction, which incorporates compression, dedupe, and single instancing, is also included as standard and enabled by default to further increase the effective capacity.

The F210 is based on the 1U R660 PowerEdge server platform, with a single socket Intel Sapphire Rapids CPU.

The node’s front panel has limited functionality compared to older platform generations and simply allows the user to join a node to a cluster and display the node name once the node has successfully joined.

An F210 node’s serial number can be found either by viewing /etc/isilon_serial_number or via the following CLI command syntax. For example:

# isi_hw_status | grep SerNo
  SerNo: HVR3FZ3

The serial number reported by OneFS will match that of the service tag attached to the physical hardware and the /etc/isilon_system_config file will report the appropriate node type. For example:

# cat /etc/isilon_system_config
PowerScale F210

Under the hood, the F210’s core hardware specifications are as follows:

Attribute F210 Spec
Chassis 1RU Dell PowerEdge R660
CPU Single socket, 12 core Intel Sapphire Rapids 4410Y @2GHz
Memory 128GB Dual rank DDR5 RDIMMS (8 x 16GB)
Journal 1 x 32GB SDPM
Front-end network 2 x 100GbE or 25GbE
Back-end network 2 x 100GbE or 25GbE
NVMe SSD drives 4

The node hardware attributes can be gleaned from OneFS by running the ‘isi_hw_status’ CLI command. For example:

f2101-1# isi_hw_status -c

  HWGen: PSI

Chassis: POWEREDGE (Dell PowerEdge)

    CPU: GenuineIntel (2.00GHz, stepping 0x000806f8)

   PROC: Single-proc, 12-HT-core

    RAM: 102488403968 Bytes

   Mobo: 0MK29P (PowerScale F210)

  NVRam: NVDIMM (NVDIMM) (8192MB card) (size 8589934592B)

 DskCtl: NONE (No disk controller) (0 ports)

 DskExp: None (No disk expander)

PwrSupl: PS1 (type=AC, fw=00.1B.53)

PwrSupl: PS2 (type=AC, fw=00.1B.53)

While the actual health of the CPU and power supplies can be quickly verified as follows:

# isi_hw_status -s

Power Supplies OK

Power Supply PS1 good

Power Supply PS2 good

CPU Operation (raw 0x881B0000)  = Normal

Additionally, the ‘-A’ flag (All) can also be used with ‘isi_hw-status’ to query a plethora of hardware and environmental information.

Node and drive firmware versions can also be checked with the ‘isi_firmware_tool’ utility. For example:

f2101-1# isi_firmware_tool --check

Ok

f2101-1# isi_firmware_tool --show

Thu Oct 26 11:42:32 2023 - Drive_Support_v1.46.tgz

Thu Oct 26 11:42:58 2023 - IsiFw_Package_v11.7qa1.tar

The internal layout of the F210 chassis with the risers removed is as follows:

The cooling is primarily driven by four dual-fan modules, which can be easily accessed and replaced as follows:

Additionally, the power supplies also contain their own air flow apparatus, and can be easily replaced from the rear without opening the chassis.

For storage, each PowerScale F210 node contains four NVMe SSDs, which are currently available in the following capacities and drive styles:

Standard drive capacity SED-FIPS drive capacity SED-non-FIPS drive capacity
1.92 TB TLC 1.92 TB TLC

3.84 TB TLC 3.84 TB TLC

7.68 TB TLC 7.68 TB TLC

15.36 TB QLC Future availability 15.36 TB QLC

Note that a 15.36TB SED-FIPS drive option is planned for future release. Additionally, the 1.92TB drives in the F210 can also be short-stroke formatted for node compatibility with F200s containing 960GB SSD drives. More on this later in the article.

The F210’s NVMe SSDs populate the drive bays on the left front of the chassis, as illustrated in the following front view (with bezel removed):

Drive subsystem-wise, OneFS provides NVMe support across PCIe lanes, and the SSDs use the NVMe and NVD drivers. The NVD is a block device driver that exposes an NVMe namespace like a drive and is what most OneFS operations act upon, and each NVMe drive has a /dev/nvmeX, /dev/nvmeXnsX and /dev/nvdX device entry  and the locations are displayed as ‘bays’. Details can be queried with OneFS CLI drive utilities such as ‘isi_radish’ and ‘isi_drivenum’. For example:

f2101-1# isi_drivenum
Bay 0   Unit 3      Lnum 0     Active      SN:BTAC2263000M15PHGN   /dev/nvd3
Bay 1   Unit 2      Lnum 2     Active      SN:BTAC226206VB15PHGN   /dev/nvd2
Bay 2   Unit 0      Lnum 1     Active      SN:BTAC226206R515PHGN   /dev/nvd0
Bay 3   Unit 1      Lnum 3     Active      SN:BTAC226207ER15PHGN   /dev/nvd1
Bay 4   Unit N/A    Lnum N/A   N/A         SN:N/A              N/A
Bay 5   Unit N/A    Lnum N/A   N/A         SN:N/A              N/A
Bay 6   Unit N/A    Lnum N/A   N/A         SN:N/A              N/A
Bay 7   Unit N/A    Lnum N/A   N/A         SN:N/A              N/A
Bay 8   Unit N/A    Lnum N/A   N/A         SN:N/A              N/A
Bay 9   Unit N/A    Lnum N/A   N/A         SN:N/A              N/A

As shown, the four NVMe drives occupy bays 0-3, with the remaining six bays unoccupied. These four drives and their corresponding PCI bus addresses can also be viewed via the following CLI command:

f2101-1# pciconf -l | grep nvme
nvme0@pci0:155:0:0:     class=0x010802 card=0x219c1028 chip=0x0b608086 rev=0x00 hdr=0x00
nvme1@pci0:156:0:0:     class=0x010802 card=0x219c1028 chip=0x0b608086 rev=0x00 hdr=0x00
nvme2@pci0:157:0:0:     class=0x010802 card=0x219c1028 chip=0x0b608086 rev=0x00 hdr=0x00
nvme3@pci0:158:0:0:     class=0x010802 card=0x219c1028 chip=0x0b608086 rev=0x00 hdr=0x00

Comprehensive details and telemetry for individual drive are available via the ‘isi_radish’ CLI command using their /dev/nvdX device entry. For example, for /dev/nvd0:

f2101-1# isi_radish -a /dev/nvd0
Drive log page ca: Intel Vendor Unique SMART Log
              Key                              Attribute                                         Field                                                 Value
============================== ======================================== 
(5.0) (4.0)=(171) (0.0)              Program Fail Count                 Normalized Value                                        100
(5.0) (4.0)=(171) (0.1)                                                 Raw Value                                               0
(5.0) (4.0)=(172) (0.0)              Erase Fail Count                   Normalized Value                                        100
(5.0) (4.0)=(172) (0.1)                                                 Raw Value                                               0
(5.0) (4.0)=(173) (2.0)              Wear Leveling Count                Normalized Value                                        100
(5.0) (4.0)=(173) (2.1)                                                 Min. Erase Cycle                                        2
(5.0) (4.0)=(173) (2.2)                                                 Max. Erase Cycle                                        14
(5.0) (4.0)=(173) (2.3)                                                Avg. Erase Cycle                                        5
(5.0) (4.0)=(184) (1.0)              End to End Error Detection Count   Raw Value                                               0
(5.0) (4.0)=(234) (3.0)              Thermal Throttle Status            Percentage                                              0
(5.0) (4.0)=(234) (3.1)                                                 Throttling event count                                  0
(5.0) (4.0)=(243) (1.0)              PLL Lock Loss Count                Raw Value                                               0
(5.0) (4.0)=(244) (1.0)              NAND sectors written divided by .. Raw Value                                               3281155
(5.0) (4.0)=(245) (1.0)              Host sectors written divided by .. Raw Value                                               1445498
(5.0) (4.0)=(246) (1.0)              System Area Life Remaining         Raw Value                                               0
Drive log page de: DellEMC Unique Log Page

              Key                              Attribute                                         Field                                                 Value
============================== ======================================== ======================================================= ==================================================
(6.0)                            DellEMC Unique Log Page                Log Page Revision                                       2
(6.1)                                                                   System Aread Percent Used                               0
(6.2)                                                                   Max Temperature Seen                                    48
(6.3)                                                                   Media Total Bytes Written                               110097292328960
(6.4)                                                                   Media Total Bytes Read                                  176548657233920
(6.5)                                                                   Host Total Bytes Read                                   164172138545152
(6.6)                                                                   Host Total Bytes Written                                48502864347136
(6.7)                                                                   NAND Min. Erase Count                                   2
(6.8)                                                                   NAND Avg. Erase Count                                   5
(6.9)                                                                   NAND Max. Erase Count                                   14
(6.10)                                                                  Media EOL PE Cycle Count                                3000
(6.11)                                                                  Device Raw Capacity                                     15872
(6.12)                                                                  Total User Capacity                                     15360
(6.13)                                                                  SSD Endurance                                           4294967295
(6.14)                                                                  Command Timeouts                                        18446744073709551615
(6.15)                                                                  Thermal Throttle Count                                  0
(6.16)                                                                 Thermal Throttle Status                                 0
(6.17)                                                                  Short Term Write Amplification                          192
(6.18)                                                                  Long Term Write Amplification                           226
(6.19)                                                                  Born on Date                                            06212022
(6.20)                                                                  Assert Count                                            0
(6.21)                                                                  Supplier firmware-visible hardware revision             5
(6.22)                                                                  Subsystem Host Read Commands                            340282366920938463463374607431768211455
(6.23)                                                                  Subsystem Busy Time                                     340282366920938463463374607431768211455
(6.24)                                                                  Deallocate Command Counter                              0
(6.25)                                                                  Data Units Deallocated Counter                          165599450
Log Sense data (Bay 2/nvd0 ) --
Supported log pages 0x1 0x2 0x3 0x4 0x5 0x6 0x80 0x81

SMART/Health Information Log
============================
Critical Warning State:         0x00
 Available spare:               0
 Temperature:                   0
 Device reliability:            0
 Read only:                     0
 Volatile memory backup:        0
Temperature:                    307 K, 33.85 C, 92.93 F
Available spare:                100
Available spare threshold:      10
Percentage used:                0
Data units (512,000 byte) read: 320648767
Data units written:             94732208
Host read commands:             3779434531
Host write commands:            1243274334
Controller busy time (minutes): 33
Power cycles:                   93
Power on hours:                 2718
Unsafe shutdowns:               33
Media errors:                   0
No. error info log entries:     0
Warning Temp Composite Time:    0
Error Temp Composite Time:      0
Temperature 1 Transition Count: 0
Temperature 2 Transition Count: 0
Total Time For Temperature 1:   0
Total Time For Temperature 2:   0

SMART status is threshold NOT exceeded (Bay 2/nvd0 )
NAND Write Amplification: 2.269913, (Bay 2/nvd0 )

Error Information Log
=====================
No error entries found
Bay 2/nvd0  is Dell Ent NVMe SED P5316 RI 15.36TB FW:1.2.0 SN:BTAC226206R515PHGN, 30001856512 blks

                Attr                          Value
=================================== =========================
NAND Bytes Written                  3281155
Host Bytes Written                  1445498

Drive Attributes: (Bay 2/nvd0 )

In contrast, the rear of the F710 chassis contains the power supplies, network, and management interfaces, which are laid out as follows:

The F210 nodes are available in the following networking configurations, with a 25/100Gb ethernet back-end and 25/100Gb ethernet front-end:

Front-end NIC Back-end NIC F210 NIC Support
100GbE 100GbE Yes
100GbE 25GbE No
25GbE 100GbE Yes
25GbE 25GbE Yes

Note that there is currently no support for an F210 Infiniband backend in OneFS 9.7.

These NICs and their PCI bus addresses can be determined via the ’pciconf’ CLI command, as follows:

f2101-1# pciconf -l | grep mlx
mlx5_core0@pci0:23:0:0: class=0x020000 card=0x005815b3 chip=0x101d15b3 rev=0x00 hdr=0x00
mlx5_core1@pci0:23:0:1: class=0x020000 card=0x005815b3 chip=0x101d15b3 rev=0x00 hdr=0x00
mlx5_core2@pci0:111:0:0:        class=0x020000 card=0x005815b3 chip=0x101d15b3 rev=0x00 hdr=0x00
mlx5_core3@pci0:111:0:1:        class=0x020000 card=0x005815b3 chip=0x101d15b3 rev=0x00 hdr=0x00

Similarly, the NIC hardware details and drive firmware versions can be view as follows:

f2101-1# mlxfwmanager
Device #1:
----------
  Device Type:      ConnectX6DX
  Part Number:      0F6FXM_08P2T2_Ax
  Description:      Mellanox ConnectX-6 Dx Dual Port 100 GbE QSFP56 Network Adapter
  PSID:             DEL0000000027
  PCI Device Name:  pci0:23:0:0
  Base GUID:        a088c20300052a3c
  Base MAC:         a088c2052a3c
  Versions:         Current        Available
     FW             22.36.1010     N/A
     PXE            3.6.0901       N/A
     UEFI           14.29.0014     N/A
  Status:           No matching image found

Device #2:
----------
  Device Type:      ConnectX6DX
  Part Number:      0F6FXM_08P2T2_Ax
  Description:      Mellanox ConnectX-6 Dx Dual Port 100 GbE QSFP56 Network Adapter
  PSID:             DEL0000000027
  PCI Device Name:  pci0:111:0:0
  Base GUID:        a088c2030005194c
  Base MAC:         a088c205194c
  Versions:         Current        Available
     FW             22.36.1010     N/A
     PXE            3.6.0901       N/A
     UEFI           14.29.0014     N/A
  Status:           No matching image found

Performance-wise, the new F210 is a relative powerhouse compared to the F200. This is especially true for NFSv3 streaming reads, as can be seen below:

OneFS node compatibility provides the ability to have similar node types and generations within the same node pool. In OneFS 9.7, compatibility between the F210 nodes and the previous generation F200 platform is supported.

Component F200 F210
Platform R640 R660
Drives 4 x SAS SSD 4 x NVMe SSD
CPU Intel Xeon Silver 4210 (Cascade Lake) Intel Xeon Silver 4410Y (Sapphire Rapids)
Memory 96GB DDR4 96GB DDR5

This compatibility facilitates the addition of individual F210 nodes to an existing node pool comprising three of more F200s if desired, rather creating a F210 new node pool. Despite the different drive subsystem across the two platforms, and the performance profiles above. Because of this, however, the F210/F200 node compatibility is slightly more nuanced, and the F210 NVMe SSDs are considered ‘soft restriction’ compatible with the F200 SAS SSDs. Additionally, the 1.92TB is the smallest capacity option available for the F210, and the only supported drive configuration for F200 compatibility.

In compatibility mode the 1.92Tb drives will be short stroke formatted, resulting in a 960 GB capacity per drive.​ Also note that, while the F210 is node pool compatible with the F200, a performance degradation is experienced where the F210 is effectively throttled to match the performance envelope of the F200s. ​

When an F210 is added to the F200 node pool, OneFS will display the following WebUI warning message alerting to this ‘soft restriction’:

And similarly from the CLI:

PowerScale All-flash F710 and F210 Platform Nodes

Hot on the heels of the recent OneFS 9.7 release sees the launch of two new PowerScale F-series hardware offerings. Between them, these new F710 and F210 all-flash nodes add some major horsepower to the PowerScale stable.

Built atop the latest generation of Dell’s PowerEdge R660 platform, the F710 and F210 each boast a range of Gen4 NVMe SSD capacities, paired with a Sapphire Rapids CPU, a generous helping of DDR5 memory, and PCI Gen5 100GbE front and back-end network connectivity – all housed within a compact, power-efficient 1RU form factor chassis.

Here’s where these new nodes sit in the current hardware hierarchy:

As illustrated in the greyed out region of the above chart, these new nodes refresh the current F600 and F200 platforms, and further extend PowerScale’s price-performance envelope.

The PowerScale F210 and F710 nodes offer a substantial hardware evolution from previous generations, while also focusing on environmental sustainability, reducing power consumption and carbon footprint. Housed in a 1RU ‘Smart Flow’ chassis for balanced airflow and enhanced cooling, both new platforms offer greater density than their F600 and F200 predecessors – the F710 now accommodating ten NVMe SSDs per node and 25% greater density, and the F210 now offering NVMe drives with a 15.36 TB option, and doubling the F200’s maximum density. Both platforms also include in-line compression and deduplication by default, further increasing their capacity headroom and effective density. Plus, using Intel’s 4th gen Xeon Sapphire Rapids CPUs results in 19% lower cycles-per-instruction, while PCIe Gen 5 quadruples throughput over Gen 3, and the latest DDR5 DRAM offers greater speed and bandwidth – all netting up to 90% higher performance per watt. Additionally, the F710 and F210 debut a new 32 GB Software Defined Persistent Memory (SDPM) file system journal, in place of NVDIMM-n in prior platforms, thereby saving a DIMM slot on the motherboard too.

On the OneFS side, the recently launched 9.7 release delivers a dramatic performance bump – particularly for the all-flash platforms. OneFS 9.7 benefits from latency-improving enhancements to its locking infrastructure and protocol heads – plus ‘direct write’ non-cached IO, which we will explore in a future article.

This combination of generational hardware upgrades plus OneFS 9.7 software advancements results in dramatic performance gains for the F710 and F210 – particularly for streaming reads and writes, which see a 2x or greater improvement over the prior F600 and F200 platforms. This makes the F710 and F210 ideal candidates for demanding workloads such as M&E content creation and rendering, high concurrency and low latency workloads such as chip design (EDA), high frequency trading, and all phases of generative AI workflows, etc.

Scalability-wise, both platforms require a minimum of three nodes to form a cluster (or node pool), with up to a maximum of 252 nodes, and the basic specs for the new nodes include:

Component PowerScale F710 PowerScale F210
CPU Dual–socket Intel Sapphire Rapids, 2.6GHz, 24C Single–socket Intel Sapphire Rapids, 2GHz, 12C
Memory 512GB DDR5 DRAM 128GB DDR5 DRAM
SSDs per node 10 x NVMe SSDs 4 x NVMe SSDs
Raw capacities per node 38.4TB to 307TB 7.7TB to 61TB
Drive options 3.84TB, 7.68TB TLC and 15.36TB, 30.72TB QLC 1.92TB, 3.84TB, 7.68TB TLC and 15.36TB QLC
Front-end network 2 x 100GbE or 25GbE 2 x 100GbE or 25GbE
Back-end network 2 x 100 GbE 2 x 100GbE or 25GbE

Note that, while the F210 can coexist with the F200 in the same node pool, the F710 does not currently have any node pool compatibility peers.

Over the next couple of articles, we’ll dig into the technical details of each of the new platforms. But, in summary, when combined with OneFS 9.7, the new PowerScale all-flash F710 and F210 platforms quite simply deliver on efficiency, flexibility, performance, and scalability.

OneFS and Externally Managed Network Pools – Management and Monitoring

In the first article in this series, we took a look at the overview and architecture of the OneFS 9.7 externally managed network pools feature. Now, we’ll turn our focus to its management and monitoring.

From a cluster security point of view, the externally managed IP service has opened up a potential new attack vector whereby a rogue DHCP server could provide bad data. As such, the recommendation is to configure a firewall around this new OneFS DHCP service to ensure that the cluster is protected. While the OneFS firewall could in theory provide this protection, in order to know what the DHCP server is, the cluster first has to discover and talk to the DHCP server and get its IP. This seems a bit paradoxical (and insecure) to be creating a firewall rule after having already talked to and trusted the DHCP server.

The following table contains recommended configuration settings for the AWS firewall.

Setting Value
Name Eg. ‘DHCP”
Type ‘ingress’
From Port 67
To Port 68
Protocol UDP
CIDR Blocks <cluster_gateway>/32
IPv6 CIDR Blocks []
Security Group ID // customer specific

Note that, as mentioned in the first article in this series, there are a currently a couple of instances of unsupported networking functionality in the APEX file services for AWS offering, as compared to on-prem OneFS, and these include:

  • IPv6 support
  • VLANs
  • Link aggregation
  • NFSoverRDMA

These limitations for externally managed network pools are highlighted in red below, and are read-only settings since they are managed by the cloud provider (interfaces and IPs).

Externally managed network pools can only be created by the system with OneFS 9.7 and therefore pools cannot be manually reconfigured either to or from externally managed – even by root.

In general manual IP configuration is protected in order to guard against accidental misconfiguration. However, clusters admin may occasionally be required to manually configure the IPs in the network pool, and can be performed with the ‘isi network pool modify’ plus the inclusion of the ‘–force’ flag:

# isi network pool modify subnet0.pool0 –ranges <ip_add_range> --force

Note that AWS has a maximum threshold for the number of IPs that can be configured per network interface based on AMI instance type. If this limit is exceeded, AWS will prevent the IP address from being configured, resulting in a potential data unavailability event.  OneFS 9.7 now prevents most instances of IP oversubscription at configuration time in order to ensure availability during a 1/3 cluster outage.

While OneFS accounts for externally managed, static, dynamic IPs, and SSIPs, it is unable to account for unevenly allocated dynamic IPs, so it’s therefore unable to prevent all instances.

OneFS also displays an informative error message if attempting to configure this. For example, using an AMI instance type of ‘m5d.large’:

# isi network pool modify subnet0.pool0 –ranges 10.20.30.203-10.20.30.254

AWS only allows node 2 (instance type AWS=m5d.large) to have a maximum of 10 IPv4 addresses configured. In a degraded state, the requested configuration will result in node 2 attempting to configure 28 addresses, which will leave 18 address(es) unavailable. To resolve this, consider increasing the number of nodes in dynamic pools or reducing the number of IPv4 addresses.

When it comes to troubleshooting externally managed pools, there are two log files which are useful to check. Namely:

  • /var/log/dhclient.log
  • /var/log/isi_smartconnect

The first of these is a dedicated dhclient.log file for the new dhclient instance that OneFS 9.7 introduces. In contrast, the IP Merger and IP Reporter modules will output to the isi_smartconnect log.

There are also a handful of relevant system files that are also worth being aware of, and these include:

  • /var/db/dhclient/lease.ena1
  • /ifs/.ifsvar/modules/flexnet/ip_reporter/DHCP/node.
  • /ifs/.ifsvar/modules/flexnet/pool_members/groupnet.1.subnet.1.pool.1
  • /ifs/.ifsvar/modules/smartconnect/resource/workers/ip_merger

The first of these, lease.ena1, is an append log maintained by dhclient. So the most recent lease in there is the one that is SmartConnect is looking at. Note that there may be other lease files in the system, but only the lease files in /var/db/dhclient are relevant, and being viewed by SmartConnect. OneFS has a special configuration for dhclient to ensure this.

The IP reports live in the /ifs/.ifsvar/modules/flexnet directory. The pool_members directory has been present in OneFS for a number of years now. And OneFS now coordinates the IP merger with the file under ./smartconnect/resource/workers/ directory.

As for useful CLI commands, these include the following:

# isi_smartconnect_client action –a wake-ip-reporter

The ‘isi_smartconnect_client’ CLI utility, which can be used to interact with the SmartConnect daemon, gets an additional ‘wake-ip-reporter’ action in OneFS 9.7. Under normal circumstances, the IP Reporter only checks the contents of the lease file every five minutes. However, ‘wake-ip-reporter’ now instructs IP Reporter to check the lease file immediately. So if there was some issue where dhclient restarted for some reason, IP Reporter can be awoken and forced to read the lease, rather than waiting for its next scheduled check.

Additionally, the following ‘log_level’ command arguments can be used to change the logging level of SmartConnect to the desired verbosity:

# isi_smartconnect_client log_level [-l | -r]

Note that, in OneFS 9.7, this does not change the Flexnet config file which was required in prior releases.

Instead, this log level is reset when the process dies or the ‘–r’ argument is passed. It’s worth noting that this command does not operate cluster-wise. Rather, it just affects the current instance of SmartConnect running on the local node.

Another thing to be aware of when a cluster is using externally managed pools is that networking is dependent on, and can be impacted by, the availability of AWS’ DHCP servers. While the leased IP never changes, the leases themselves have an expiration of an hour. As such, if OneFS is unable to reach the DHCP server to renew, it may lose its Primary IPs. While this is often outside the realm of control, the OneFS CELOG event service will fire a critical warning alert (SW_SC_DHCP_LEASE_REBIND) before a primary IP expires. This alert will contain the following event description:

DHCP server has not responded to requests to renew lease on <interface>. Attempting to contact other DHCP servers. If we are unable to renew the lease, the IP address <ip_address> will be removed at expiry.

For example:

In addition to the above alert, there are several log messages that give a good indication of what may be amiss. These, and their resolution info, are summarized in the following table:

Log Message Description Resolution
Unable to merge IP 1.2.3.4 on ext-1 from devid 1 – no matching pool found IP is not configured in any Network Pool Add IP to the Primary IP Pool
Unable to parse lease on NIC: ena1. Attempting to retrieve new lease The lease file generated by dhclient could not be read. None should be required. We will automatically backup the old lease file and restart dhclient
Lease on NIC: ena1 not found Lease file does not exist for the specified interface OneFS will automatically restart dhclient
Unexpected error comparing IP Reports. Attempting rewrite We try to dedupe writes by comparing newly generated IP report with what is on disk. In the event of a failure, we’ll just overwrite.
No IP Report received from DHCP External Manager OneFS unable to determine its IP from the DHCP leases. Will continue retrying, but currently unable to report an IP If issues persists, check on dhclient to ensure it is operating correctly.
Failed to write IP Report node. for DHCP to disk: OneFS unable to report its IP to /ifs, so the IP merger is unable to update Flexnet/IP Assignments with this information. Check why SmartConnect is unable to write to /ifs. Is it read only?

 

OneFS and Externally Managed Network Pools

Tucked amongst the array of new functionality within OneFS 9.7’s payload is the debut of a networking feature called externally managed network pools. In layman’s terms, this is essentially the introduction of a front-end dynamic host control protocol (DHCP) client for the PowerScale cluster.

The context and motivation behind implementing this new functionality is predicated on the fact that cloud networking differs substantially from on-prem infrastructure. This is largely because the cloud hyperscalers typically require a primary IP to be configured on a specific interface that they dictate. Normally, systems operating within an off-prem environment obtain their network configuration via the DHCP protocol. But as you’re likely aware, until OneFS 9.7, DHCP has not been supported on a cluster’s front end network previously. To support APEX file services for AWS, OneFS 9.6 implemented a manual work-around for this, which had its limitations. However, with OneFS 9.7, the desire was to make the system smarter and by adding proper support for IPv4 primary IP addresses on AWS deployments, thereby negating the need for configuring manual work-arounds, with their inherent risks.

This new externally managed IP addresses feature is automatically enabled upon committing and upgrade to OneFS 9.7. To support this feature, a new network allocation method has been added to OneFS’ network pools called ‘externally managed’. This is actually managed by an external service such as AWS, which dictates where these primary IPs live. So they are in charge of IP allocation, rather than the cluster’s Flexnet or SmartConnect services, which has been the case up to now. It’s worth noting that OneFS 9.7 only includes (and enforces) limited DHCP support, strictly for cloud deployments currently. That said, on-prem DHCP support may be added in a future release but this is currently not on the near-term roadmap. Additional work was also included in OneFS 9.7 to prevent IP oversubscription.

So let’s take a look under the hood… Architecturally, there are three main components to the externally managed IP addresses feature:

  • DHCP Service
  • IP Reporter Module
  • IP Merger Module

OneFS 9.7 actually talks DHCP by leveraging the FreeBSD ‘dhclient’ implementation. Dhclient is modified so it does not actually configure the network interfaces like it would normally, in order to avoid conflicts with the OneFS Flexnet network config daemon. Instead, dhclient just persists the leases to the following files:

  • /ifs/.ifsvar/modules/flexnet/flx_config.xml
  • /ifs/.ifsvar/modules/flexnet/pool_members/groupnet.1.subnet.1.pool.1.

Additionally, SmartConnect sees the addition of two new modules, IP Reporter and IP Merger.

Component Details
DHCP service Adds new MCP-controlled DHCP service: dhclient-ext-1

– Uses modified FreeBSD dhclient implementation

– Does not configure network interfaces

– Persists leases to /var/db/dhclient/

IP Merger Adds new cluster-wide module to SmartConnect, IP Merger:

– Coordinates ownership of the role by taking locks on files on /ifs

– Loads all files from IP Reports directory

– Verifies network pool is configured correctly and generates IP Assignments

– Updates the following files:

▪ /ifs/.ifsvar/modules/flexnet/flx_config.xml

▪ /ifs/.ifsvar/modules/flexnet/pool_members/groupnet.1.subnet.1.pool.1

IP Reporter Adds new module to each node’s SmartConnect service:

– Parses DHCP leases

– Converts to a generic format

– Saves to /ifs/.ifsvar/modules/flexnet/ip_reports/DHCP/node.

These modules are still part of the overarching isi_smartconnect_d, and just new components within that same daemon. The IP Reporter module will parse the above lease files and then save the information to /ifs/.ifsvar/modules/flexnet/ip_reports/DHCP/node.

In contrast, the IP Merger is a single cluster-wide instance that loads the files from the IP Reports directory, verifies the network pool configuration, generates the IP assignments, and updates the config files. The ip_merger file contains the devID of the node that has been elected as responsible for IP merging. The full path is as follows:

/ifs/.ifsvar/modules/smartconnect/resource/workers/ip_merger

The following CLI syntax can be used to determine which node is acting as the merger: For example:

# isi_for_array 'grep "Taking ownership of the IPMerger role" /var/log/isi_smartconnect’

TME-4:  2024-02-07T16:26:20.946863+00:00 <3.6> GLaDOS-4(id4) isi_smartconnect_d[3626]: Taking ownership of the IPMerger role

In this case, the command output indicates that node ID4 has taken ownership of the IPMerger role.

The underlying process is very similar to how OneFS manages SSIPs in that all nodes attempt to lock a file under /ifs, and one granted that lock, they own that responsibility.  So OneFS takes the files from under /ifs/.ifsvar/modules/flexnet/ip_reports and merges the IP information into the Flexnet config and the pool members file, as follows:

The above graphic illustrates how data flows through the system from the cloud provider’s DHCP server, to dhclient, and then into isi_smartconnect_d. The modular, extensible architecture requires only a small portion of OneFS to be made aware of this new type of network pool. This all happens on the side until the data is merged into the Flexnet config and the associated state files, so it is low risk to everything else.

In OneFS 9.7, this new DHCP allocation method is now set as ‘externally managed’  for subnet0.pool0. This can be seen even on network pools that have been upgraded from an earlier OneFS release. Additionally, the CLI output also reports the type of external manager for this network pool – for instance AWS in the example below:

The ‘isi network interfaces’ CLI syntax is also updated in OneFS 9.7 to allow filtering by ‘externally managed’ pools. For example below, again showing that the owner is AWS:

As a quick reminder, there are a currently a couple of instances of unsupported networking functionality in the APEX file services for AWS offering, as compared to on-prem OneFS, and these include:

  • IPv6 support
  • VLANs
  • Link aggregation
  • NFSoverRDMA

In the next article in this  series we’ll turn our attention to the management, monitoring, and security of OneFS 9.7 externally managed network pools.

OneFS SmartSync Configuration for Google Cloud

As we saw in the previous blog in this series, with the inclusion of Google Cloud (GCP) in OneFS 9.7, SmartSync Cloud Copy now supports all three of the principal public cloud hyperscalers.

Object data replication to Google Cloud (GCP) can be configured in OneFS 9.7 via the ‘isi dm accounts create’ CLI command. Required information includes the regular account configuration parameters plus the following GCP-specific settings:

  • GCP account type
  • GCP URI
  • Access ID
  • Secret key

Or, more specifically:

Parameter Description
Object store type GCP (or AWS_S3, Azure, ECS_S3, etc)
URI {http,https}://hostname:port/bucketname
Auth Access ID, Secret Key
Proxy Optional proxy information

For example:

# isi dm account create --account-type GCP --name [Account Name] --access-id [GCP access-id] --uri [GCP URI with bucket-name] --auth-mode CLOUD --secret-key [GCP secret-key]

Once created, the new account can be verified with the following command:

# isi dm accounts list

Additionally, the next steps for SmartSync configuration and policy creation are covered in detail in the following blog article.

SmartSync Cloud Copy supports both push and pull replication, permitting the same dataset that is copied to GCP with a push to be copied back to the cluster via a corresponding pull.

Be aware that a dataset must be available before a policy runs, or the policy will fail.

Also note that, while multiple GCP URIs and credentials are supported by SmartSync, they are not supported on the same account. Multiple accounts and multiple corresponding policies would need to be created for SmartSync.

Other SmartSync features and functionality includes:

Feature Details
Bandwidth throttling Set of netmask rules. Limits are per-node.
CPU throttling Allowed and Back-off CPU percentages.
Base policies Template providing common values to groups of related policies (schedule, source base path, enable/disable, etc). Ie. Disabling base policy affects all linked concrete policies.
Concrete policy Predefined set of fields from the base policy
Unconnected nodes (NANON) Active accounts are monitored by each node. No work allocation to nodes without network access.
Snapshot locking Avoids accidental snapshot deletion, with subsequent re-base-lining.

Behind the scenes, dataset creation leverages a SnapshotIQ snapshot, which can be inspected via the ‘isi snapshot list’ command. These DM dataset snapshots are easily recognizable due to their ‘isi_dm’ prefixed naming convention.

The SmartSync Cloud Copy format provides both regular file representation, browsability and usability of file system data in the cloud. In addition to the replication of the actual data, SmartSync also preserves the common file attributes including Windows ACLs, POSIX permissions and attributes, creation times, extended attributes, etc. However, there are certain considerations and limitations to be aware of, such as no incremental copy. These also include:

CloudCopy Caveats Details
ADS files Skipped when encountered.
Hardlinks An object will be created for each link (ie. links are not preserved).
Symlinks Skipped when encountered.
Directories An object is created for each directory.
Special files Skipped when encountered.
Metadata Only POSIX mode bits, UID, GID, atime, mtime, ctime are preserved.
Filename encodings Converted to UTF-8.
Path Path relative to root copy directory is used as object key.
Large files An error is returned for files larger than the cloud providers maximum object size.
Long filenames File names exceeding 256 bytes are compressed.
Long paths Junction points are created when paths exceed 1024 bytes to redirect where objects are being stored
Sparse files Sparse sections are not preserved and are written out fully as zeros.

SmartSync allows subsequent incremental data movement by managing and re-transferring failed file transfers. Similarly, Dataset reconnect enables systems with common base datasets to establish instant incremental syncs. SmartSync also proactively locks the SnapshotIQ snapshots it uses, providing better separation between Datamover and other snapshots.

Performance-wise, SmartSync is powered by a scalable run-time engine, spanning the cluster, and which spins up threads (fibers) on demand and uses asynchronous IO to process replication tasks (chunks). Batch operations are used for efficient small file, attribute, and data block transfer. Namespace contention avoidance, efficient snapshot utilization, and separation of dataset creation from transfer are salient design features of the both the baseline and incremental sync algorithms.

OneFS SmartSync and Google Cloud Support

Another feature addition that OneFS 9.7 delivers is support for Google Cloud (GCP) as a target for SmartSync, PowerScale’s next-gen data mover. With this enhancement, SmartSync Cloud Copy now supports all three of the principal public cloud hyperscalers – Amazon S3, Google Cloud Platform, and Microsoft Azure.

As you may be aware, this is not OneFS’ first foray into Google Cloud integration. CloudPools has supported GCP as a remote tiering target for several years now. Also, from the SmartSync perspective, while GCP represents a new account type, it fits within the existing cloud authentication mechanism, plus also uses an object protocol spec that’s based heavily on Amazon’s S3.

CloudCopy uses HTTP as the data replication transport layer to cloud storage, while traditional cluster to cluster SmartSync leverages a proprietary RCP-based messaging system.

In order to use SmartSync with GCP, the cluster must be running OneFS 9.7 and have SyncIQ licensed and active across all nodes in the cluster. Additionally, a cluster account with the ISI_PRIV_DATAMOVER privilege is needed in order to configure and run SmartSync data mover policies. While file-to-file replication requires SmartSync to be running on both source and target clusters, for OneFS Cloud Copy to transfer to/from cloud storage, only the cluster requires the SmartSync platform, and no data mover is required on the cloud systems. Be aware that the inbound TCP 7722 IP port must be open across any intermediate gateways and firewalls to allow SmartSync replication to occur.

Under the covers, replication is executed by the ‘isi_dm_d’ service, and the SmartSync data mover’s basic architecture is as follows:

The ‘isi_dm_d’ service is disabled by default and needs to be enabled prior to configuring and using SmartSync. SmartSync also uses TLS (transport layer security, or SSL) and, as such, requires trust to be established between the cluster and cloud target.

The SmartSync Datamover also includes a purpose-build, integrated scheduler and job control and execution framework, which operates along these lines:

Shared Key-Value Stores (KVS) are used for jobs/tasks distribution, and extra indexing is implemented for quick lookups by task state, task type, and alive time. There are no dependencies or communication between tasks, and job cancellation and pausing is handled by posting a ‘request’ into a job record (request polling).

Within the SmartSync hierarchy, accounts define the connections to remote systems, policies define the replication configurations, and jobs perform the work, or tasks:

Component Details
Accounts Datamover accounts:

–          URI, eg. dm://remotenas.isln.com:7722

–          Network pools defining nodes/interfaces to use for data transfer

–          Client and server certificates to enable TLS

CloudCopy accounts:

–          Account type (AWS S3, Azure, GCP, ECS S3)

–          URI, eg. https://cloudcluster.isln.com:9002/cloudbucket

–          Credentials

Policies –          Dataset creation policy

–          Dataset copy policy

–          Dataset repeat copy policy

–          Dataset expiration policy

Jobs Runtime entities created based on policies schedules. There are two major types of data transfer jobs:

–         Baseline jobs for initial transfers and

–         Incremental jobs for subsequent transfers between FILE Datamover systems.

Tasks Spawned by jobs and are the individual chunks of work that a job must perform. No 1-to-1 relationship to their associated files.

So, in order to configure SmartSync to use GCP as a cloud target, the following prerequisites are required:

Requirement Detail
Account GCP account and credentials to use with feature
License SyncIQ license across the cluster
OneFS version OneFS 9.7 or higher installed and committed for GCP..
Privileges Cluster account with the ISI_PRIV_DATAMOVER role to configure & manage.

While SmartSync is automatically installed in OneFS 9.4 and later, it is inactive by default. As such, there is no impact from the feature unless it is enabled.

To verify that GCP support is available, the account type will be listed in the output of from the ‘isi dm account create –help’ CLI command.

For example,:

# uname -sr

Isilon OneFS 9.7.0.0

# isi dm account create --help | grep -i gcp

    <account-type> (DM | AWS_S3 | ECS_S3 | AZURE | GCP)

Currently, SmartSync configuration is limited to the CLI or platform API, with WebUI support planned for a future release. As such, configuration is typically performed via the ‘isi dm’ CLI utility, which contains the following the principal subcommands:

Subcommand Description
isi dm accounts Manage Datamover accounts. An activate SyncIQ license is required to create Datamover accounts.
isi dm base-policies Manage Datamover base-policy. Base policies are templates to provide common values to groups of related concrete Datamover policies. Eg. Define a base policy to override the run schedule of a concrete policy.
isi dm certificates Manage Datamover certificates.
isi dm config Show Datamover Manual Configuration.
isi dm datasets Show Datamover Dataset Information.
isi dm historical-jobs Manage Datamover historical jobs.
isi dm jobs Manage Datamover jobs.
isi dm policies Manage Datamover policy. Policies can be either:

CREATION – Creates/replicates a dataset, either once or on a schedule.

COPY – Defines a one-time copy of a dataset to or from a remote system

isi dm throttling Manage Datamover bandwidth and CPU throttling. Bandwidth throttling rules can be configured for each Datamover job.

In the next article in this series, we’ll look at the configuration required to use SmartSync with Google Cloud (GCP).

OneFS Cluster Configuration Backup and Restore – Operation and Management

The previous article in this series took a look at the enhancements and supporting architectural changes to OneFS cluster configuration backup and restore in the OneFS 9.7 release. Now, we’ll focus on its operation and management.

By default, the cluster configuration backup and restore files reside at:

File Location
Backup file /ifs/data/Isilon_Support/config_mgr/backup/<JobID>/<component>_<JobID>.json
Restore file /ifs/data/Isilon_Support/config_mgr/restore/<JobID>/<component>_<JobID>.json

The log file for configuration manager is located at /var/log/config_mgr.log and can be useful to monitor the progress of a config backup and restore, especially for any troubleshooting purposes.

So let’s take a look at this cluster configuration management process:

The following example steps through the export and import of a cluster’s NFS and SMB configuration – within the same cluster. This can be accomplished as follows:

  1. First, create some SMB shares and NFS exports using the following CLI commands:
# isi smb shares create --create-path --name=test --path=/ifs/test

# isi smb shares create --create-path --name=test2 --path=/ifs/test2

# isi nfs exports create --paths=/ifs/test

# isi nfs exports create --paths=/ifs/test2
  1. Next, export the NFS and SMB configuration using the following CLI command:
# isi cluster config exports create --components=nfs,smb --verbose
The following components' configuration are going to be exported:
['nfs', 'smb']
Notice:
    The exported configuration will be saved in plain text. It is recommended to encrypt it according to your specific requirements.
Do you want to continue? (yes/[no]): yes
This may take a few seconds, please wait a moment
Created export task ' PScale-20240118105345'

From the above, the job ID for this export task is ‘ PScale-20240118105345’.

As the warning indicates, the configuration backup is saved in plain text. However, sensitive information is not exported.

  1. The results of the export operation can be verified with the following CLI command, using the job ID for this operation:
# isi cluster config exports view PScale-20240118105345
     ID: PScale-20240118105345
 Status: Successful
   Done: ['nfs', 'smb']
 Failed: []
Pending: []
Message:
   Path: /ifs/data/Isilon_Support/config_mgr/backup/PScale-20240118105345
  1. The JSON files can be viewed under /ifs/data/Isilon_Support/config_mgr/backup/PScale-20240118105345.
# ls /ifs/data/Isilon_Support/config_mgr/backup/PScale-20240118105345
backup_readme.json             
nfs_PScale-20240118105345.json 
smb_PScale-20240118105345.json

Note that OneFS generates a separate configuration backup JSON file for each component (ie. SMB and NFS in this example), plus a readme file which provides a synopsis of the backup operation.

  1. The SMB shares and NFS exports can be deleted as follows:
# isi smb shares delete test

# isi smb shares delete test2

# isi nfs exports delete 9

# isi nfs exports delete 10
  1. The prior SMB and NFS configuration can now be easily restored with the following CLI syntax:
# isi cluster config imports create PScale-20240118105345 --components=nfs,smb --verbose
Source Cluster Information:
          Cluster name: PScale
       Cluster version: 9.7.0.0
            Node count: 4
  Restoring components: ['nfs', 'smb']
Notice:
    Please review above information and make sure the target cluster has the same hardware configuration as the source cluster, otherwise the restore may fail due to hardware incompatibility. Please DO NOT use or change the cluster while configurations are being restored. Concurrent modifications are not guaranteed to be retained and some data services may be affected.
Do you want to continue? (yes/[no]):
This may take a few seconds, please wait a moment
Created import task 'PScale-2024011810345'
  1. To view the restore results, use the following command:
# isi cluster config imports view PScale-20240118105345
       ID: PScale-20240118110659
Export ID: PScale-20240118105345
   Status: Successful
     Done: ['nfs', 'smb']
   Failed: []
  Pending: []
  Message:
     Path: /ifs/data/Isilon_Support/config_mgr/restore/ PScale-20240118110659
  1. Finally, verify that the SMB shares and NFS exports are restored:
# isi smb shares list
Share Name  Path
----------------------
test        /ifs/test
test2       /ifs/test2
----------------------
Total: 2

# isi nfs exports list
ID   Zone   Paths      Description
-----------------------------------
11   System /ifs/test
12   System /ifs/test2
-----------------------------------
Total: 2

Currently, cluster configuration backup and restore is only available via the CLI and platform API. However, a WebUI management component is planned for a future release, as is the ability to run a diff, or comparison, between two exported configurations.

One other significant enhancement to cluster configuration backup and restore is the support for custom network rules for restoring subnet IP addresses, allowing cluster admins to assign different IP address from backup for restoring a new subnet. This ensures that a network restore will not overwrite any existing subnets and pools’ IP addresses on the target cluster, thereby avoid connectivity breaks. The CLI syntax for specifying cluster configuration restore custom network rules is as follows:

# isi cluster config imports create \ --components network \ --network-subnets-ip <string>

For example, the following CLI syntax will configure the target cluster’s groupnet0.subnet1 network to use 10.1.10.0 and a netmask of 255.255.255.252 and its groupnet1.subnet0 to use 10.2.20.0 with a netmask of 255.255.255.0:

# isi cluster config imports create \ --components network \ --network-subnets-ip "groupnet0.subnet1:10.1.10.0/22,groupnet1.subnet0:10.2.20.0/24"

When it comes to troubleshooting the cluster config backup and restore, the first place to check is the output of the ‘isi cluster config exports|imports view’ CLI commands. The backups themselves can be found under /ifs/data/Isilon_Support/config_mgr/backup/. After this, the next place to look for information is the log file, located at /var/log/config_mgr.log. Additionally, the job database, which resides at /ifs/.ifsvar/modules/config_mgr/config.sqlite, can also be queried in a pinch. However, exercise caution since this job DB should not be modified under any circumstances.