possible NFS lockups

krad kraduk at googlemail.com
Tue Jul 27 15:29:22 UTC 2010

I have a production mail system with an nfs backend. Every now and again we
see the nfs die on a particular head end. However it doesn't die across all
the nodes. This suggests to me there isnt an issue with the filer itself and
the stats from the filer concur with that.

The symptoms are lines like this appearing in dmesg

nfs server not responding
nfs server is alive again

trussing df it seems to hang on getfsstat, this is presumably when it tries
the nfs mounts


__sysctl(0xbfbfe224,0x2,0xbfbfe22c,0xbfbfe230,0x0,0x0) = 0 (0x0)
mmap(0x0,1048576,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) =
1746583552 (0x681ac000)
mmap(0x682ac000,344064,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) =
1747632128 (0x682ac000)
munmap(0x681ac000,344064)                        = 0 (0x0)
getfsstat(0x68201000,0x1270,0x2,0xbfbfe960,0xbfbfe95c,0x1) = 9 (0x9)

I have played with mount options a fair bit but they dont make much
difference. This is what they are set to at present     /mail/0 nfs
rw,noatime,tcp,acdirmax=320,acdirmin=180,acregmax=320,acregmin=180 0       0

When this locking is occuring I find that if I do a show mount or mount again under another mount point I can access it

One thing I have just noticed is that lockd and statd always seem to have
died when this happens. Restarting does not help

I find all this a bit perplexing. Can anyone offer any help into why this
might be happening. I have dtrace compliled into the kernel if that could
help with debugging

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