Occasionally my drives will not show in Windows Explorer even though they appear online (Reserved) and mapped to a drive letter in Disk Management. I'm not sure what makes them come back but right now I have no way to get to them.
I'm remoted in to the active node and even if I try typing the drive letter in in Windows Explorer (e.g. K:\
) I still can't get to the drive. The passive node doesn't show them either, in case you're wondering.
I recently switched my SQL Server 2012 cluster (Windows Server 2008 R2) SAN from a VNX to an XtremIO but not sure it's related to the problem. I never noticed the problem before though.
I'm not using Cluster Shared Volumes as far as I know (the SMB share thing...I'm definitely talking about volumes shared across two clustered servers).
UPDATE 12/22/15: I discovered that if I remote in with a different account (same permissions) I can see all the drives. I'm still baffled.