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After upgrading to ESX/ESXi 4.1, the default pathing policy for LUNs that are used with MSCS is set to Round Robin (1033678)

Symptoms

After installing or upgrading to ESX/ESXi 4.1, you experience these symptoms on LUNs that are mapped as RDMs and used by MSCS as shared storage:

  • The default Path Policy is set to Round Robin
  • The quorum disk experiences problems and the cluster may not operate
  • This issue occurs in, but is not limited, LUNs presented from Hitachi, NetApp, and IBM

Resolution

This is an expected behavior because the Round Robin path policy is not supported for LUNs that are used with MSCS. For more information, see Setup for Failover Clustering and Microsoft Cluster Service.
 
The default Path Selection Policy was changed by the upgrade to ESX/ESXi 4.1 since the corresponding storage vendors have requested changing the default claim rules to use VMW_PSP_RR for their Storage Arrays.
 
For a supported configuration, you must change the pathing policy for these LUNs to Fixed or MRU. For example, if the array is Active/Passive, use the MRU Path Policy and if the array is Active/Active, use the Fixed Path Policy.

You can change the pathing policy to MRU or Fixed using the command-line or vSphere Client.

To change the pathing policy using the vSphere Client:

  1. Connect the vSphere Client to the ESX host or vCenter Server.
  2. Select a host in the left pane and click the Configuration tab.
  3. Under Hardware, click Storage Adapters.
  4. Select a Fiber Channel HBA from the list.
  5. Right-click the LUN for which you want to change the Path Selection Policy and click Manage Paths.
  6. Depending on the type of array, select Fixed or MRU from the Path Selection dropdown.
  7. Repeat these steps for LUNs on each host that is a part of a cluster with MSCS virtual machines.

To change the pathing policy using the command-line, see Changing a LUN to use a different Path Selection Policy (PSP) (1036189).

Tags

change-PSP-MSCS

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