We were showing a high level of NFS errors - lock file creation errors, lock file access errors and APD states.
StorageApdHandler: 421: Device or filesystem with identifier [xxxxxxxx-xxxxxxxx has exited the All Paths Down state.
WARNING: NFSLock: 2226:
Cannot create lock file .lck-6200000000000000 (4 retries) : Not found
As it turned out, the firmware for the VIC / enet needed to be updated. An update to the firmware for the UCS blade to version 2.1.3b fixed this issue.