Prior to vSphere 5.5 the Round Robin Path Selection Policy (VMW_PSP_RR) is not supported for the shared disks of a Microsoft cluster. You may find that the ESXi multipathing claim rules are set so that when the RDMs are discovered the PSP is automatically set to Round Robin, so you will want to change this. You will probably want to keep the Round Robin PSP for the other non-shared clustered disks such as LUNs used for VMFS volumes therefore you probably do not want to change the default claim rules.
From vSphere 5.5 the Round Robin PSP is supported for the clusters shared disks.
There is also a NetApp KnowledgeBase article that states that ALUA should not be enabled on the igroup when using Microsoft clustering with shared RDMs prior to vSphere 5.5. See https://kb.netapp.com/support/index?page=content&id=2013316. They have 3 solutions: –
- Disable ALUA on the igroup for the ESXi hosts with Microsoft Windows Clustered servers.
- Use dedicated initiators for the shared clustered RDMs with ALUA disabled and different initiators for the other LUNs such as VMFS volumes and non-shared RDMs.
- Use iSCSI within the Windows Servers for the shared disks.