On Wed, 2004-03-31 at 13:14, Devdas Bhagat wrote:
> On 31/03/04 10:44 +0530, Manvendra Bhangui wrote:
> <snip>
> > Sun E3500 with 6 CPU, Solaris 8, vxfs (1 terrabyte of disk space,
> Multiple CPUs do not help a mail server. More spindles help.
I have plenty of spindles (Sun Storedge T3). It is just that
I have around few millions of directories on this server. Also
this server is something I inherited and did not want to waste it.
It is only because of qmail, I am able to use this legacy server.
But for the same amount of delivery, postfix overall took more
CPU. Shot my load up. Required daily reboot. My uptime went down. I
frequently saw smtpd, cleanup, trivial-rewrite, master
qmgr frequently coming in the top 10 processes. My users complained. I
gave up on postfix.
There is no problem with the design. My architecture is horizontally
scalable. I have other users on other servers (all intel PIII, etc).
None of them have any performance problem. I have no problem running
qmail, imapd, pop3d, on the same box. The only care I take
is to have my queue on RAID 0
>
> > and around 1.2 Million Users and around 27 million mails lying
> > on the server). The reason I wanted to try postfix was because it
> 27 million in your queue? In mailboxes? The same box also offers
> pop3/imap and content filtering?
27 Million files lying in user's mailboxes
Yes the same box offers pop3 and imap
Content filtering is done by qmail on my MX (these are separate
boxes)
> Sounds like you didn't configure Postifx for performance then.
Well I did the same for qmail. It performed better.
> What was your smtpd process limit set to?
It was set to 1000 (same as for qmail in tcpserver)
>
> > postfix for a month and gave up after plenty of user complaints.
> With
> > the EXT-TODO extension to qmail, qmail would handle the high
> incoming
> > rate easily. With very high svc_t and my disks always 100% blocked,
> it
> > made a big difference running qmail. Though the IO did not improve,
> but
> > at least the CPU came down drastically when using qmail.
> CPU? Postfix hardly uses CPU at all, unless you are doing content
> filtering within Postfix.
>
This is a wrong assumption on your part. postfix also uses the stdio
library. Postfix is Maruti 800. qmail is Rolls Royce. If you are
a good C programmer, you will understand that.
> <snip>
> > Another point to note that with postfix, I had a tough time with
> > syslogd. Postfix uses syslog() function to log everything. And
> syslog is
> > a performance PIG. with qmail you can use multilog
> You mean you don't understand how syslog(3) works, and how to tune
> performance.
I did everything, async option, etc. It is very simple to hog the CPU
using syslog() function. Just try this 6 lines of C code
#include <syslog.h>
main()
{
char buffer[256];
long tmval;
while(1)
{
tmval = time(0);
snprintf(buffer, sizeof(buffer), "How I hog the CPU at %s",
ctime(&tmval));
syslog(LOG_ERR, buffer);
}
}
Do the same thing for multilog (replace syslog with fprintf)
and pipe the output to multilog
>
> > http://cr.yp.to/daemontools.html
> >
> > After my experience with multilog, I encourage people to write all
> > error messages to stderr. multilog takes care of rest.
> Ugh, ugly as hell. syslog over TCP to a remote box.
Why should I waste another box just for syslog ? Just because it
screws up IO and CPU.
>
> > > * Were you running a local dns cache, or was the resolver running
> on
> > > another box on the same switch?
> >
> > local dns cache
> >
> I see a lot of design issues in here for a badly tuned mail server.
> This is actually addressed in the Postfix FAQ.
Maybe. But I am quite happy with qmail. I have qmail, postfix and
sendmail. I am a C Programmer. The qmail code is a beauty. The qmail
design is again a beauty. The design is exactly like unix. You can
use the commands just like ls | more. In postfix, the various process
are tightly coupled by a tight interprocess communication.
1. Take smtp transaction from a file
qmail-smtpd < /tmp/smtp.txt
2. Send mail to a remote server without queing on the disk
cat /tmp/mail.txt | qmail-remote lists.sourceforge.net \
[EMAIL PROTECTED] [EMAIL PROTECTED]
> Devdas Bhagat
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