kernel hanging problem - nfs?...

Wesley T. Perdue wes at greenfieldnetworks.com
Thu Dec 26 14:39:00 CST 2002


Linux PowerEdge users,

I've got a problem on a PE 2400 running Red Hat 7.1 w/ kernel 2.4.7-10smp; it has two PIII cpus.

The PE 2400 is as home directory and mail server, and therefore sees a lot of nfs traffic to fifteen other servers, eight of which are nodes in a compute cluster.    The PE 2400 has a built-in PERC, and the home dir filesystem is on a RAID-5 array made up of 3x73 GB HDs recently purchased from Dell.  I took the defaults when configuring the array.  I updated the PERC firmware last year to v.2.5.  The root filesystem is on a separate RAID-5 array on the same controller - 3x9 GB, I think.

The problem seems to have surfaced after moving the home dir filesystem to the new array, possibly because the newly available space has brought more users to their home directories from the space-starved working directories on another server.

When nfs traffic gets high, the load (as reported in uptime and top) goes very high (into the tens or twenties), even though there aren't that many active processes.  There are a number of nfsd processes (maybe eight) taking a bit of cpu each.  The machine can feel unresponsive at this time.

Sometimes, the machine will hang for a number of seconds (say, up to 30) -- absolutely nothing responds, not even the console.  When this happens, the disk I/O lights are flashing very busily.  When the server snaps out of it, the load is _very_ high, and then gradually comes down.


Any assistance would be deeply appreciated.

Regards,
Wes

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Wes Perdue
IT Manager, Greenfield Networks




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