We have been able to bring /nv/pc5 back online, but at a cost to redundancy. One of the network interfaces/cables/switches is not behaving, but when we tried disconnecting various combinations of cables, we found one that caused the filesystem to be immediately available to all nodes.
Considering how close maintenance day is (10/16/12), spending time isolating the cable/switch/interface problem now only means more time for this filesystem to be offline as equipment gets retested. Waiting until maintenance day will cause the least disruption for Cygnus pc5 users who have their last run of jobs and take some time pressure off of us to make sure we have resolved the issue in its entirety before bringing all resources back online.
Despite the loss of redundancy, functionality is NOT affected. Only in the case of an additional switch or cable failure between now on October 16 will functionality be impacted.