High IOWAIT
I'm running Plesk 7.5 on a Debian Sarge box. It has been running just
fine for the last few months, but for the last week or two users have
been complaining about slow mail delivery. Mail messages appear to be
received just fine, but don't get written into the target Maildirs for
anywhere from 2 to 6 hours after receipt.
I can't find anything obvious wrong with the system, except for this:
this is a dual-CPU machine with hyperthreaded CPUs, so "top" reports 4
CPUs. Every time I run "top" it shows either 40-50% IOWait on all
virtualCPUs, or near 0 IOWait on one virtual pair and near 100% on the
other.
I haven't seen any hardware error messages in the logs, and I'm sort of
at a loss as to what could be causing this ridiculous IOWait. Any
suggestions?
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