Date: Wed, 7 Feb 2001 13:31:26 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Dan Phoenix <dphoenix@bravenet.com> Cc: Andrew Reilly <areilly@bigpond.net.au>, Alfred Perlstein <bright@wintelcom.net>, Andre Oppermann <oppermann@monzoon.net>, Rik van Riel <riel@conectiva.com.br>, Mike Silbersack <silby@silby.com>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Charles Randall <crandall@matchlogic.com>, Jos Backus <josb@cncdsl.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: vinum and qmail (RE: qmail IO problems) Message-ID: <200102072131.f17LVQv94265@earth.backplane.com> References: <Pine.BSO.4.21.0102071309260.9863-100000@gandalf.bravenet.com>
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Well, that's a jump. You never said how bumping maxusers went!
However, we have finally gotten a clue to how much mail you are pushing..
600MB in a day. That sure doesn't sound like something I would want
to run a machine with an IDE drive. Why not just buy one of those
supercool 2U VALINUX boxes (they can run FreeBSD as easily as Linux)
and stuff two or three SCSI disks into it?
The disk activity we are seeing here, assuming the file descriptor and
network issues have been fixed, can only be from the mail traffic and
the fsync() calls the MTA makes. It's beginning to sound unavoidable,
and I'm not sure how the linux box could possibly have done better
short of them not implementing the fsync() system call.
In anycase, while VINUM is great for striping disks I recommend that
you use CCD to begin with, because CCD is a whole lot less complex.
You can stripe IDE drives but the two drives must be on different IDE
controllers (not just primary secondary, but each drive must be primary
on its own controller). Then striping will help.
Of course, I would not recommend using IDE at all if you are pushing
600MB/day in mail. You really should be using a SCSI based system...
something like the VALINUX boxes (running either Linux or FreeBSD).
I am still interested in mail transfer rate numbers for what you were
doing on the Linux box verses what you are doing now. With that much
mail, even a few hours of downtime can create a huge backlog. I am
not entirely convinced that you aren't seeing the backlog but without
more information (do you have aggregate statistics from your mail logs
for the last few months, for example?), it's hard to diagnose.
-Matt
:I went over to postfix to see if it did better.....in fact it did on
:freebsd but still same problem with I/O. SOlution from talking to some
:people late last night would be to add another harddrive and stripe it
:with another drive using vinum. As you all know IDE does not do
:multitasking unlike scsi. My question is this vinum product...i beleive
:the superceder of ccd....taking another harddrive and striping it with the
:root ide drive would in theory destroy all contents of first IDE?
:Or can this volume manager take say a partition of first ide drive and
:made to work with another ide drive? Trying to figure out at this point
:whether concept is 2 other drives striped together say..using raid 0 or
:I can get away with just one other one. Thx in advance.
:
:ps. 600 megs of email was calculated in 1 day on this machine...today i
:will be splitting up the load and looking into vinum.
:
:Regards,
:
:Dan
:
:
:On Wed, 7 Feb 2001, Andrew Reilly wrote:
:
:> Date: Wed, 7 Feb 2001 14:12:25 +1100
:> From: Andrew Reilly <areilly@bigpond.net.au>
:> To: Alfred Perlstein <bright@wintelcom.net>
:> Cc: Andre Oppermann <oppermann@monzoon.net>,
:> Matt Dillon <dillon@earth.backplane.com>,
:> Rik van Riel <riel@conectiva.com.br>, Mike Silbersack <silby@silby.com>,
:> Poul-Henning Kamp <phk@critter.freebsd.dk>,
:> Charles Randall <crandall@matchlogic.com>,
:> Dan Phoenix <dphoenix@bravenet.com>, Jos Backus <josb@cncdsl.com>,
:> freebsd-hackers@FreeBSD.ORG
:> Subject: Re: soft updates and qmail (RE: qmail IO problems)
:>
:> On Tue, Feb 06, 2001 at 12:13:57PM -0800, Alfred Perlstein wrote:
:> > * Andre Oppermann <oppermann@monzoon.net> [010206 12:07] wrote:
:> > > Does sendmail even use fsync()?
:> >
:> > It better. :)
:>
:> Quick grep of the sendmail sources shows most of the six fsync
:> calls protected by a flag (SuperSafe && or nofsync &&). I don't
:> know what circumstances can provoke either of those flags to be
:> zero, but if they can be, then it mightn't be doing any fsyncs.
:>
:> --
:> Andrew
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