[ccp4bb]: NFS Performance

[Martin Singleton <singleto@cancer.org.uk>]

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Dear All

We have recently started using Linux (RedHat 7.2) machines in our SGI
based network.
All of our user accounts are held on an NFS exported filesystem from an
SGI server. This filesystem is mounted on the Linux machine as well as the
other SGIs. Linux sees the filesystem fine, but there appears to be a
major performance problem when certain CCP4 programs as well as SOLVE on
the Linux box requires access to this filesystem. The problem seems to
occur during read/writes of large binary files, which cause programs to
slow to a crawl, in some cases increasing the run time by two orders of
magnitude. I have noticed that the programs processor usage often drops to
< 1% when this occurs and the machine rapidly runs out of memory (1GB
real!) If the same process is run on the local (ext3) disc only, or on the
SGI machines, there are no such problems. Obviously the problem lies with
the Linux-IRIX disc cross-mounting, but so far I have not been able to see
where, and the documented NFS options do not seem to help. Has anyone else
noticed this problem, or suggest any solutions ?

Regards

Martin Singleton
Cancer Research UK
Clare Hall Laboratories,
South Mimms,
Herts EN6 3LD
martin.singleton@cancer.org.uk