nfsd4: utime sometimes takes 40+ seconds to return (but on SLES11SP3 with kernel 3.0.82)

[Joschi Brauchle <joschi.brauchle@tum.de>]

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Hello everyone,

we are administrating an NFS high-availability cluster running on 
SLES11SP1 with kernel 2.6.32.59. Just recently, one of the cluster 
machines was updated to SLES11SP3 with kernel 3.0.82.


We are now experiencing severe hangs on NFS clients when the SLES11SP3 
server is running the NFS services. An strace on the hanging processes 
on the client side show that is is waiting up to 60+ seconds for a 
"utime()" call to complete.


The problem we see is matching the problem described in the thread "v3.5 
nfsd4 regression; utime sometimes takes 40+ seconds to return". If the 
NFS server is running on SLES11SP3, the little test program provided in 
this tread hangs at the "utime()" call for 60+ seconds. It hangs each 
time it is run! It finishes right away with 0 seconds delay is SLES11SP1 
is providing NFS services, each time.


Now, in the serverside logfiles of SLES11SP3 we see these messages (not 
so on SP1):
--------------
kernel: [99381.184976] RPC: AUTH_GSS upcall timed out.
kernel: [99381.184978] Please check user daemon is running.
--------------

We have always been running the NFS server without rpc.gssd on the 
server side, as the init script for the nfsserver also does not start 
rpc.gssd.


Once we started rpc.gssd on the SLES11SP3 server, using the test utility 
on the client shows that the first call to "utime()" succeeds right 
away, the second call takes ~25s to complete. But now, any consecutive 
runs of the utility finish with no more delay.


So can anyone confirm that with kernel 3.0+ the rpc.gssd daemon is also 
required on the server side for correct operation?

Has there been a change between kernel 2.6.32.59 and 3.0.x?

Thus, is the init script of the nfsserver in SLES11SP3 indeed missing to 
start rpc.gssd?

Thank you for your help!

Best regards,
-- 
Dipl.-Ing. Joschi Brauchle, M.S.

Institute for Communications Engineering (LNT)
Technische Universitaet Muenchen (TUM)
80290 Munich, Germany

Tel (work): +49 89 289-23474
Fax (work): +49 89 289-23490
E-mail: joschi.brauchle@tum.de
Web: http://www.lnt.ei.tum.de/



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