Our five node Hyper-V cluster is connected to a Dell MD3000i, which provides virtual machine storage using Cluster Shared Volumes (CSV).  The MD3000i has dual storage controllers for redundancy, but recently both storage controllers rebooted within a minute of each other.  Looking at the Storage section of Failover Cluster Manager showed that half the CSV volumes had a status of Redirected Access.  Reading this blog http://blogs.technet.com/b/askcore/archive/2010/12/16/troubleshooting-redirected-access-on-a-cluster-shared-volume-csv.aspx showed that the first thing to try was to “Turn off redirected access for this Cluster shared volume”, unfortunately this didn’t work.  I looked in Disk Management on each of the five nodes, which looked as below:

Each node should be able to see all the disks, but only the first node, the one on the far left, could see all five disks.  I live migrated the virtual machines off each node and rebooted each node one at a time.  Once completed, Disk Management looked like this:

Every node can see all five disks.  I checked Failover Cluster Manager and all the CSV volumes had returned to Online status automatically.