Since Friday afternoon, we have been experiencing an issue with the QRIScloud NFS servers. This is manifesting as intermittent "access denied" or "permission denied" errors, and in some cases "stale file handle" errors. In addition, people who have added SSH keys to their collection VMs may be blocked from logging in using them.
At this point, we have not been able to diagnose the problem. Operations staff will resume their investigation on Monday morning.
As a temporary workaround, a "wait a bit and try again" strategy often seems to be effective. The problem is only known to be affecting 4 collections at the moment.
UPDATE (18/05/2015 - 9:30) - RCC has reported that a possible cause of the problem has been identified. At this stage, I have no ETA for a fix.
UPDATE (18/05/2015 - 10:00) - RCC is now working on the fix.
UPDATE (18/05/2015 - 10:30) - The fix for the problem has now been deployed.