I've recently built three WS2012 Hyper-V clusters with Dell EqualLogic storage. The cluster builds were straight forward and are performing well.
The same issue has happened on all three whenever doing the push install of the VMM agent to the hosts and adding the cluster to VMM. On each occasion the cluster volumes on the Dell EqualLogic were taken offline for a period, causing the virtual machines on the volumes to pause in a critical state.
After SCVMM was finished adding the hosts, the volumes could be brought back online and the virtual machines started. Bit heart stopping though the first time it happened!
Whilst it happened, lots of errors event ID 5120, 5142, 1557, 1558, and 1069 appeared in the logs of each host - basically relating the volumes going offline, but not helping to point out how or why.
In all of the cluster builds affected "Do not allow cluster communication for this network" has been selected for the iSCSI network.
The VMM logs had the following "Completed w/ Info" warning for each host after adding the cluster "Warning (26211) A restart is required to complete claiming of multi-path I/O devices on host <host FQDN>).
I'm wondering if there is something strange happening with the new SMP storage management capabilities of VMM 2012 SP1? I didn't ask VMM to try to manage the storage whilst adding the Hyper-V hosts, so why it should interfere with the storage I don't know :(
Anyone ran into something similar? Would like to get to the bottom of it as Hyper-V with Dell EqualLogic storage is a very common build for us.