NFS file server has hanged tasks, which causes problems for clients, which also tend to hang. Since this is a Linux kernel bug, csfs needs a restart. During the restart /cs/fs and /cs/group2 file shares are unavailable.

UPDATE 13:30: An update to nfs-kernel-server was broken and kerberos autentication stopped working. It took 2 hours to figure out that this was a case and to track down an older debian package to fix this. Now kerberos authetication works again, but old mounts still need fixing. A reboot fixed things, but we are still looking for a better solution.

UPDATE 14:15: Now everything should be working again as usual. Sorry about the trouble. Time to file a debian bug report.