Memory use

[Glenn Steen]

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On 17/11/05, José Angel Blanco González <jose at treelogic.com> wrote:
> I detect slow performance when sometimes the machine stops responding imap
> and pop connections. I think the preoblem is slow disk read/write
> operations.
> Some user have shared accounts and maintain a server copy, but they download
> the mayl by pop, I think they must use imap
>
> Jose

Thanks José.

During those "sometimes" is the machine otherwise responsive? You
should try to get some stats for those exact times. Look at CPU,
memory usage, swap, IO and network performance during such a hiccup,
if possible.

This might mean you need to setup the sar package to run for an
extended period of time, leave vmstat running (dumping to a file),
same with iostat... And perhaps get ntop or a similar tool (I think
IBMs nmon for linux might give you a "one-stop-shopping tool";).
There's some stuff about things like this in the wiki (the maq and
performance tuning bits).... Have a look there.

Depressing but true: Troubleshooting performance problems rarely are
fixed by a "quick fix", but more often by knowing, through stats and
docs, exactly what is up and fixing just that. Iow: tweaking, not
frobbing:-):-).
Then again, just to confirm the rule by exception, one do get lucky
from time to time whilst frobbing;-).

Depending on what level of control you have over the client side, you
should perhaps take "a long thought" on what protocols you do want to
support, and the ramifications (POPs badness vs IMAPs .... mainly
inefficiency vs having all mail stored on the server side, more or
less).

--
-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se

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