At 11:20 AM 6/28/2001 +0800, PM WONG wrote:
>We run qpopper 3.0.2 on an AIX unix box. As most users choose
>to keep mails on server, hence it becomes quite slow when plenty
>users are reading their mail at the same time (though i've
>placed the .pop files directory separate from their /var/spool/mail
>mailboxes).
>Now since the newest version of AIX OS has this feature of
>using part of the RAM as disk (using a command called mkramdisk)
>, i wonder will it improve things much ( i did a simple test
>on a test machine for 1 mailbox, but the difference is not significant)
>for qpopper. Could it be that the reading of the mail from /var/spool/mail
>to create the .pop files is also the bottleneck.
>Any comments?
If you can run in server mode, that avoids copying the spool file
when there is no new email. If you update to 4.0.x you can avoid
even reading the spool file in the case of no email.
On AIX you can make mirrored and distributed disks. This speeds
up mail reading iff the temporary drop spool is also distributed. Otherwise,
the temp spool becomes a bottleneck when many large mail boxes are
being read at once (all those copies have a single disk destination, and can
quickly become IO bound). I eventually moved the temp files to back to the
mail spool, since that was a faster disk (mirrored and distributed).
And, again, under 4.0.x a move will be used instead
of a copy if the spool and lock are on the same disk, speeding things up
again.
I have not experimented with ram disks, but if you have the memory, making
your temp drop a ram disk should be faster. There will still be a reading
bottleneck. Qpopper 3 reads the spool file from beginning to end during
each pop. But at least the temp file write will be faster. A mirrored mail
spool will speed up the mailbox scan since the reading can come from
either of the disk mirrors.
Finally, we went to SSA disks for our spool. And, on the new machine I'll
be setting up a RAID01 using SSA, instead of using the logical volume
manager. I've been using the SSA RAID on our webmail server, and it's
been very very good to us. :-) SSA costs more, but they pay for themselves
in performance and time saved.
Mike
--
Michael D. Sofka [EMAIL PROTECTED]
CIS/SSS Sr. Systems Programmer email, webmail, listproc, TeX, epistemology.
Rensselaer Polytechnic Institute, Troy, NY. http://www.rpi.edu/~sofkam/
