If it's ls -l rather than just ls, slow user or group lookups can also have an effect. If the client supports nscd, that should be checked to see that it's caching user and group info usefully. That is a case of name services issues, whether the underlying name service is NIS, or LDAP, or anything other than local files. Any NFS authentication better than AUTH_SYS (simply trusting that UIDs/GIDs are the same) may have similar problems, probably as seen by the server.
Google tells me that Linux has an nfsiostat command; the RTT or exe (total execution of an NFS RPC, including RTT) look like they might be interesting numbers; find out what's normal, parse it, set thresholds accordingly. It will probably need to be a client-side script. I've never heard of nfsiostat before (having worked more on Solaris than Linux), but it sounds promising.
Ultimately, NFS is difficult to check for performance issues, because server, network, and as above with ls -l, sometimes other infrastructure can affect it or appear to affect it.
Tests like a big dd from an NFS mounted file, or a ls of a big directory (you would need one that was on every client, didn't change, and used the same server as their home directory) will likely make the problem worse, adding load to network and server. So something like nfsiostat, that just reports info already maintained by the kernel, is much safer. Pushing a client side stress test out to dozens or hundreds of clients could be easily done once written, but could make the problem MUCH worse. :-)
On Fri, Mar 4, 2016 at 11:17 AM, Paul Jochum <paul.jochum at nokia.com> wrote:
Hi Xymon List:
Does anyone know of a test script that I can add, that checks if anNFS mount is performing quickly enough? Basically, I have a few users complaining that every once in a while, an "ls" of their NFS mounted home file systems take a long time. I would like a xymon test that could check for that, in cases where a command (such as an ls of a file system) takes longer than "x" amount of time, display a warning or error.
Thank you,
Paul
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