After upgrading to ESX/ESXi 4.1, the default pathing policy for LUNs that are used with MSCS is set to Round Robin (1033678)
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
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:
- Connect the vSphere Client to the ESX host or vCenter Server.
- Select a host in the left pane and click the Configuration tab.
- Under Hardware, click Storage Adapters.
- Select a Fiber Channel HBA from the list.
- Right-click the LUN for which you want to change the Path Selection Policy and click Manage Paths.
- Depending on the type of array, select Fixed or MRU from the Path Selection dropdown.
- 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).