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Manage MPIO for Hyper-V hosts in the VMM fabric

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Read this article to learn how System Center Virtual Machine Manager (VMM) manages Multipath I/O (MPIO) on Hyper-V hosts.

When you add Fiber Channel or iSCSI storage to a Hyper-V host managed in the VMM fabric, the Multipath I/O (MPIO) feature must be enabled on each host.

  • If MPIO is enabled on the host, VMM adds it for supported storage arrays using the Microsoft DSM. If you installed vendor-specific DSMs, the vendor-specific MPIO settings will be used to connect to the storage array.
  • If you add a host and MPIO isn't enabled, VMM will show a warning message in the Jobs window.
  • If you add a host to VMM and enable MPIO afterwards, you need to add the MPIO feature, and then manually configure MPIO to add the discovered device hardware IDs. Alternatively, you can install vendor-specific DSMs.

MPIO tracking in VMM

When Hyper-V hosts and clusters are added to the VMM fabric, VMM deploys an agent to connect between the host and the VMM server. Additionally, VMM collects configuration information about the host or cluster and adds it to VMM. For MPIO, VMM adds two registry keys containing MPIO information.

  • HKEY LOCAL MACHINE\SYSTEM\CurrentControlSet\Control\MPDEV\MPIOSupportedDeviceList
  • HKEY LOCAL MACHINE\SYSTEM\CurrentControlSet\Services\msdsm\Parameters\DsmSupportedDeviceList

After supported storage devices are added to the device list, VMM makes a claim on them, and a restart is required on the host. If you've added the host to VMM before deploying workloads on it, then this probably isn't an issue, but if workloads are already running on the host, this could cause interruptions. To avoid potential outages, you can run a PowerShell script to prepopulate the MPIO registry keys on a host, before adding it to the VMM fabric. Learn more about this script.

Prevent VMM from claiming device IDs

If you don't want VMM to claim any storage device IDs for MPIO purposes, do the following:

  1. Open registry location HKLM\Software\Microsoft\Microsoft System Center Virtual Machine Manager Server\Settings.
  2. In this location, create a registry key RemoveMPIOHardwareIds with type multi-string.
  3. Add the device IDs from the default list. Ensure that you use the same spacing.
  4. Restart the VMM service.
  5. Add the Hyper-V host in the VMM.

Next steps

Provision a VM