NFS trouble on 7.3-STABLE i386

[Mark Morley]

Having an issue with a file server here (7.3-STABLE i386)

The nfsd processes are hanging.  Client access to the nfs shares stops working and the nfsd processes on the server cannot be killed by any means.  There are no errors showing up anywhere on the server.  The network connection to the server seems fine (ie: anything other than nfs traffic seems ok).  Rebooting the server fixes the problem for a while, but it doesn't reboot easily.  It times out on terminating the nfsd processes.  When it finally does reboot the file system isn't marked clean, resulting in a long wait for fsck (although it doesn't find any problems, it's a multi terrabyte share and it takes a while).

This morning it did it again.  This time I tried manually killing nfsd but nothing I did would make them die.  No errors.

The server is a dual core intel cpu with 2 gigs of ram.
Adaptec 5805 raid controller, 8 x 750G drives, RAID 6
2 x em interfaces

It's been find until about last week some time.  I did recently upgrade from 7.1 to 7.3, which may be related, although this issue didn't start happening right away.  No particular time of day and it doesn't seem to coincide with any particular cron tasks or have anything to do with the level of activity.

Any thoughts?

Mark