Does SCSI-3 PR support for VHDS in Hyper-V guest clusters depend on the underlying storage connectivity (FC vs iSCSI)?

SCSI-3 persistent reservations (PR) for Virtual Hard Disks (VHDS) in Hyper-V guest clusters can be influenced by the underlying storage connectivity, such as Fibre Channel (FC) versus iSCSI. In general, if your current setup with FC storage is functioning correctly with SCSI-3 PR, switching to iSCSI should also support SCSI-3 PR, provided that the iSCSI storage itself supports persistent reservations.

However, there are a few considerations:

• Storage Transport Type: The transport type (FC vs. iSCSI) can affect how Hyper-V exposes SCSI-3 PR features. It's essential to ensure that the iSCSI storage is configured correctly to support SCSI-3 PR.
• Configuration: While specific configurations for iSCSI-based Cluster Shared Volumes (CSV) may not be extensively documented, ensuring that the iSCSI initiators and targets are properly set up and that the storage supports SCSI-3 PR is crucial.
• Limitations: Always check for any known limitations with the specific iSCSI storage solution you are using. Microsoft documentation may provide insights into any specific requirements or configurations needed for iSCSI environments.

In summary, as long as your iSCSI storage supports SCSI-3 persistent reservations, the functionality should be similar to that of FC storage, but verifying the configuration and compatibility is essential.

References:

• Hyper-V feature compatibility by generation and guest
• Supported Windows guest operating systems for Hyper-V on Windows, Windows Server, and Azure Local

Hi Houwen He ,

Thanks for sharing the detailed environment and question!

Key points to clarify:

1. Hyper-V Host Support Windows Server 2022 Hyper-V supports guest failover clustering using shared VHDX/VHDS files over multiple storage transport options, including Fibre Channel (FC) and iSCSI. This capability has been available since Windows Server 2012 R2. Reference: https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn281956(v=ws.11)

2. Transport Type (FC vs iSCSI) From the Hyper-V perspective, the underlying transport (FC or iSCSI) does not change how shared virtual disks are exposed to guest VMs. As long as the CSV and storage layer support persistent reservations, Hyper-V will allow the guest cluster to use them.

3. Special Configuration for iSCSI CSV No additional Hyper-V-specific configuration is required beyond standard best practices for iSCSI-based clusters:

• Ensure the iSCSI storage supports SCSI-3 PR.
• Validate multipath I/O (MPIO) and network redundancy for iSCSI.
• Confirm CSV connectivity and performance.

4 Scope of Microsoft Support:
---> Microsoft supports the host and storage integration (Hyper-V cluster, CSV, FC/iSCSI connectivity).
However, SCSI-3 PR behavior inside Linux guest VMs running LifeKeeper is outside Microsoft’s support scope. For that, please confirm with:

• Linux OS vendor
• LifeKeeper support
• Storage vendor

Summary: Switching from FC to iSCSI should not affect Hyper-V’s ability to expose shared VHDX for guest clustering. If the iSCSI storage supports PR, the scenario is expected to work.
For guest-level PR implementation, consult Linux and LifeKeeper documentation.

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