Strange delays on NFS server

[Ian Thurlbeck <ian@stams.strath.ac.uk>]

Dear All

I am getting strange delays on our NFS server. Everything will
be fine for maybe 5 to 10 minutes, then saving a small text file
from a client machine will suddenly take 15 seconds or more.
Similarly, mozilla will pause accessing a page for ages ~30secs
(I assume it's poking about in ~/.mozilla). Everything pops back to 
normal afterwards. NFS server is lightly used at the moment.

System is running Fedora Core1 (2188 kernel), 3ware 7500 raid, ext3.
I have 32 nfsd processes, running NFS V3/tcp, 8192 block size,
single duplex 100Mbit etherpro. Clients have similar OS/mount opts.

I noticed a possible link to this:

http://sourceforge.net/mailarchive/message.php?msg_id=9080621

Anyone care to comment?

On the NFS FAQ it suggests raising:

# echo 262144 > /proc/sys/net/core/rmem_default
# echo 262144 > /proc/sys/net/core/rmem_max

Mine are 65536 and 131071 respectively, but the FAQ gives
strong caveats about doing this.

Here is the stats off the server (I haven't rebooted since
I switched to V3):

root@dunnet ipv4]# nfsstat -s
Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
1699297854   2          2          0          0
Server nfs v2:
null       getattr    setattr    root       lookup     readlink
907181  1% 19385896 29% 375501  0% 0       0% 5647809  8% 7246    0%
read       wrcache    write      create     remove     rename
24270181 37% 0       0% 13513519 20% 261062  0% 321986  0% 64110   0%
link       symlink    mkdir      rmdir      readdir    fsstat
119741  0% 2444    0% 1372    0% 2242    0% 125821  0% 45434   0%

Server nfs v3:
null       getattr    setattr    lookup     access     readlink
2894636  0% 61177594  3% 1701443  0% 15723650  0% 39582580  2% 47421   0%
read       write      create     mkdir      symlink    mknod
1428854462 87% 71166229  4% 763544  0% 4621    0% 18314   0% 0       0%
remove     rmdir      rename     link       readdir    readdirplus
602276  0% 1631    0% 326031  0% 169218  0% 115075  0% 698649  0%
fsstat     fsinfo     pathconf   commit
54385   0% 72137   0% 2       0% 10272411  0%

Any suggestions ?


Thanks

Ian
-- 
Ian Thurlbeck                http://www.stams.strath.ac.uk/
Statistics and Modelling Science, University of Strathclyde
Livingstone Tower, 26 Richmond Street, Glasgow, UK,  G1 1XH
Tel: +44 (0)141 548 3667           Fax: +44 (0)141 552 2079



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