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

[Su Li]

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