SNAP-4 Service Release Notes

3631346

Description: When using dynamic MSIX with NVMe protocol, the free_queues PF controller property (as described in s ection "SR-IOV Dynamic MSIX Management") is not valid and always shows 0.

Workaround: Ignore the value and assume the free_queues pool is large enough.

Keywords: NVMe; MSIX

Discovered in version: 4.4.1

-

Description: The SPDK bdev_uring is not supported. It will be supported next release.

Workaround: N/A

Keywords: NVMe

Discovered in version: 4.4.0

3817040

Description: When running nvme_controller_suspend RPC with the --timeout parameter, if timeout expires, the device is no longer operational and cannot be resumed.

Workaround: Destroy and re-create the controller.

Keywords: NVMe

Discovered in version: 4.4.0

3809646

Description: When working with a new DPA provider, when sending DMA followed by an interrupt to DPA, it wakes up before DMA is written to the buffer causing DPA to miss events.

Workaround: Add a software-based periodic wake-up mechanism.

Keywords: NVMe

Discovered in version: 4.4.0

3773346

Description: In virtio-blk controller configuration, when running with SPDK NVMe-oF initiator as a backend, an unaligned size_max value may cause memory corruption.

Workaround: size_max and seg_max values must be a power of 2.

Keywords: Virtio-blk; NVMe-oF; spdk

Discovered in version: 4.3.1

3745842

Description: When running with NVMe/TCP SPDK block device as a backend, SNAP cannot work over more than 8 cores.

Workaround: Work with Arm core mask which uses only 8 cores.

Keywords: NVMe; TCP; SPDK

Discovered in version: 4.3.1

-

Description: The container image may becomes corrupted, resulting in the container status showing as exited with the error message /usr/bin/supervisord: exec format error.

Workaround: Remove the YAML from kubelet, use crictl images to list the images and crictl rmi to remove the image. Run systemctl restart containerd and systemctl restart kubelet, then copy the YAML file again to kubelet.

Keywords: NGC; container image

Discovered in version: 4.3.1

3757171

Description: When running virtio-blk emulation with large IOs (>128K) and SPDK's nvmf initiator as a backend, IOs may fail in SPDK layer due to bad alignment.

Workaround: size_max value of virtio_blk_controller_create RPC must be set and be a power of 2.

Keywords: SPDK, virtio-blk, size_max

Discovered in version: 4.3.1

3689918

3753637

Description: SNAP container bring-up takes a long time when configured with a large number of emulations, possibly taking longer than the default NVMe driver timeout.

Workaround: Increase NVMe driver IO timeout to 300 seconds (instead of 30).

Keywords: NVMe; recovery; kernel driver

Discovered in version: 4.3.0

-

Description: NVMeTCP XLIO is currently not supported when running 64K page size kernels on the DPU Arm cores (as is the case for CentOS 8.x, Rocky 8.x, or openEuler 20.x).

Workaround: N/A

Keywords: 64K page size; NVMeTCP XLIO

Discovered in version: 4.1.0

3264154

Description: NVMeTCP XLIO is not supported when running 64K page size kernels on the DPU Arm cores (such is the case with CentOS 8.x, Rocky 8.x, or openEuler 20.x).

Workaround: N/A

Keywords: Page size; NVMeTCP XLIO

Discovered in version: 4.1.0

-

Description: NVMe over RDMA full offload is not supported.

Workaround: N/A

Keywords: NVMe over RDMA; support

Discovered in version: 4.0.0

4110943

Description: Hot-unplugging a hotplugged Virtio BLK device is not allowed unless a Virtio BLK controller has previously been created for the device.

Workaround: Create a Virtio BLK controller on the device which need to do hotunplug

Keywords: hotplug, hotunplug

Discovered in version: 4.5.0

-

Description: Some old Windows OS NVMe drivers have buggy usage of SGL support.

Workaround: Disable SGL support when using Windows OS by setting the --quirks bit 4 to 1 in snap_rpc.py nvme_controller_create RPC.

Keywords: Windows; NVMe

Reported in version: 4.4.0

2879262

Description: When the virtio-blk kernel driver cannot find enough MSI-X vectors to satisfy all its opened virtqueues, it failovers to assign a single MSI-X vector to all virtqueues which negatively impacts performance. In addition, when a large number (e.g., 64) of virtqueues are associated with a single MSI-X, the kernel may enter a soft-lockup (kernel bug) and the IO will hang.

Workaround: Always keep num_queues < num_msix. Best practice is to not set --num_queues at all when creating virtio-blk controllers, and the best-suited value is automatically chosen based on available MSI-X.

Keywords: Virtio-blk; kernel driver; MSI-X

Reported in version: 4.3.0

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Description: If PCIe devices are inserted prior to the hot-plug driver being loaded on host, the hot-plug driver in kernel version less than 4.19 does not enable the slot even if the slot is occupied (i.e., presence detected in slot status register). That is, only the presence state of the slot is changed by firmware but the PCIe slot is not enabled by the kernel after host bootup (i.e.,

So that we can't get the PCIe device by lspci on host side, and the bdf is 0 on controller.

Workaround: Add pciehp.pciehp_force=1 to the boot command line on host.

Keywords: Virtio-blk; kernel driver; hot-plug

Reported in version: 4.2.1

-

Description: RedHat/Centos 7.x does not handle "online" (post driver probe) namespace additions/removals correctly.

Workaround: Use --quirks=0x2 option in snap_rpc.py nvme_controller_create.

Keywords: NVMe; CentOS; RedHat; kernel

Reported in version: 4.1.0

-

Description: Some Windows drivers have experimental support for "online" (post driver probe) namespace additions/removal, although such support is not communicated with the device.

Workaround: Use --quirks=0x1 option in snap_rpc.py nvme_controller_create.

Keywords: NVMe; Windows

Reported in version: 4.1.0

-

Description: VMWare ESXi supports "online" (post driver probe) namespace additions/removal, only if “Namespace Management” is supported by controller.

Workaround: Use --quirks=0x8 option in snap_rpc.py nvme_controller_create.

Keywords: NVMe, ESXi

Reported in version: 4.1.0

-

Description: Ubuntu 22.04 does not support 500 VFs.

Workaround: N/A

Keywords: Virtio-blk; kernel driver; Ubuntu 22.04

Reported in version: 4.1.0

-

Description: Virtio-blk Linux kernel driver does not handle PCIe FLR events.

Workaround: N/A

Keywords: Virtio-blk; kernel driver

Reported in version: 4.0.0

3679373

Description: Virtio-blk spdk driver (vfio-pci based) does not handle PCIe FLR events.

Workaround: N/A

Keywords: Virtio-blk; SPDK driver

Reported in version: 4.3.0

-

Description: A n ew virtio-blk Linux kernel driver (starting kernel 4.18) does not support hot-unplug during traffic. Since the kernel may self-generate spontaneous IOs, on rare occasions, an issue may happen even when no traffic is explicitly being run.

Workaround: N/A

Keywords: Virtio-blk; kernel driver

Reported in version: 4.0.0

Description: SPDK NVMf/RDMA initiator fails to connect to kernel NVMf/RDMA remote target.

Workaround: Use setting spdk_rpc.py bdev_nvme_set_options --io-queue-requests=128 on SPDK configuration

Keywords: SPDK, NVMf, RDMA, kernel

Reported in version: 4.3.1

-

Description: Windows OS virtio-blk driver expects at least 64K data to be available for a single IO request

Workaround: Use seg_max and size_max parameters configuration to match requirements (`seg_max * size_max > 64K`).

Keywords: Windows, virtio-blk

Reported in version: 4.3.1

-

Description: Some old Windows OS versions have malfunctioning inbox virtio-blk driver, expects a 3-party virtio-blk driver to be pre-installed to operate properly.

Workaround: Use verified 3-party driver published by fedora (link).

Keywords: Windows, virtio-blk

Reported in version: 4.3.1

-

Description: When using hotplugged PCIe devices, after all devices are plugged, the host must be rebooted for Windows to detect all devices (some Windows versions will perform reboot automatically).

Workaround: N/A

Keywords: Hotplug, Windows.

Reported in version: 4.5.0

3748674

Description: On most modern Linux Distributions - Unplugging a PCIe function from the host while there are still inflight IOs on it, will cause virtio-blk driver to hang.

Workaround: N/A

Keywords: Hotplug, Linux.

Reported in version: 4.5.0