fsync() takes about 0.06 second ---makes Cyrus deliver slow

[David Lang]

one other thing you can try is to disable duplicate delivery supression.

just like disabling sync mode this may not be something you are willing to
do for production, but it can help you find what the bottleneck is so that
you know where to look for tweaks to improve it.

David Lang

 On Mon, 9 Sep 2002, Su Li
wrote:

> Date: Mon, 9 Sep 2002 16:34:07 -0400
> From: Su Li <sli at rim.net>
> To: 'Jure Pecar' <pegasus at telemach.net>, Su Li <sli at rim.net>
> Cc: info-cyrus at lists.andrew.cmu.edu
> Subject: RE: fsync() takes about 0.06 second ---makes Cyrus deliver slow
>
> Thanks Jure,
>
> I asked my system adm. He said I could change the hard disk to RAID1+0 which
> can problely give me 2 time faster. And I have put /spool/imap/user in a
> seprate disk already. Even if times 2, I can only get 2-3 emails per second.
> I have 15,000 users on the server. That is still slow.
>
>
>
> Su
>
> -----Original Message-----
> From: Jure Pecar [mailto:pegasus at telemach.net]
> Sent: September 9, 2002 4:27 PM
> To: Su Li
> Cc: info-cyrus at lists.andrew.cmu.edu
> Subject: Re: fsync() takes about 0.06 second ---makes Cyrus deliver slow
>
>
> On Mon, 9 Sep 2002 16:00:28 -0400
> Su Li <sli at rim.net> wrote:
>
> > I wonder is there any way to may fsync() faster? If not is there any way
> > to call fsync less often? Will using a fast hard disk help? Or will move
> > the mail store -- /spool/imap/user to a database help?
>
> For what i know, fsync() speed is directly poportional to the speed of your
> disks (avg. access time more than r/w speed). The most you can do is to keep
> different cyrus files on differet physical disks, possibly on differnet raid
> arrays. Remember, mail means lots of fsync()s means disk being the
> bottleneck. If you really need the performance, check some of the solid
> state disks available around the net.
>
>
> --
>
>
> Jure Pecar
>