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Re: Strange behaviour on 4.99.53

On Fri, 8 Feb 2008, Paul Goyette wrote:

I've actually been seeing this for a while - at least since 4.99.39 ...

Occassionally it seems that disk I/O activity just stalls. currently I've got a dump(8) running on the filesystem that contains /usr/src and /usr/obj . The dump has been running for more than 5 hours now, and it making extremely slow progress. Sometimes the dump takes 9 or 10 hours before it finishes! The hard drive activity light blinks about once a second - it should be on solid, since the machine is doing nothing else.

The dump is running under control of /usr/pkg/sysutils/amanda but I don't think amanda has anything to do with the problem. The dump command is being piped to gzip(1) and the gzip output is directed to a network socket (amanda's 'dumper' is on the other end of the socket and writing things to a disk file on a different physical drive).

I've seen similar "stalls" when gzip is trying to uncompress a file located on an NFS-mounted file system.

And recently (since installing 4.99.53 yesterday) I'm occassionally seeing long waits for pine to access my mailbox - up to 1 minute or more in one case.

Has anyone else seen similar behavior? Any clues on how to track down the cause of this slowness?

Just an added datapoint here, which may (or may not) exonerate NFS...

I just tried to HUP a process (and mistyped the PID), and the

        kill -HUP x

command took more than 10 minutes to give me a new shell prompt!

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