Does sendmail scale well?
Ryan Cruse
Will sendmail scale well for 10,000 users? 100,000 users? 1,000,000
users? How does the configureation change as it scales up and is
this an easy process?
Example:
Say I wanted to support a million users via pop3 mail and
use sendmail to send and recieve mail. How would I do this?
thanks,
-Ryan
Peter Peters
In article <4t6c6i$9...@portal.gmu.edu> rcr...@site.gmu.edu (Ryan Cruse) writes:
>Will sendmail scale well for 10,000 users? 100,000 users? 1,000,000
>users? How does the configureation change as it scales up and is
>this an easy process?
nameservers and our main WWWserver. There are a few considerations. When using
aliases restarting will take a long time. With 10.000 aliases it takes about
20 seconds to read the aliases (We use sendmail with IDA).
>Example:
> Say I wanted to support a million users via pop3 mail and
>use sendmail to send and recieve mail. How would I do this?
The problem will be the choice of a good popserver. A number of popservers
will hang in some cases. It is a know behavior. The hanging process will
disappear when the same users makes a new connection. With 10 to 50 users that
is no problem but with more than 100 it becomes a big problem. We kill old
processes every hour.
Another problem would be the diskspace for the mailqueue. With 10.000 users
there will be a lot of outstanding messages because the receiving computer
will (momentary) not accept connections. Another big user of diskspace will be
the logging.
Peter
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Jos Backus
Hello Ryan,
rcr...@site.gmu.edu (Ryan Cruse) wrote:
>Will sendmail scale well for 10,000 users? 100,000 users? 1,000,000
>users? How does the configureation change as it scales up and is
>this an easy process?
>
>Example:
>
> Say I wanted to support a million users via pop3 mail and
>use sendmail to send and recieve mail. How would I do this?
I would dump sendmail and use qmail/qmail-pop3d.
Do an
echo subscribe | mail djb-qmailb...@koobera.math.uic.edu
to get more information.
Cheers,
Jos
postm...@oce.nl
--
Jos Backus _/ _/_/_/ R-IS/SNB
_/ _/ _/ Oce-Nederland B.V.
_/ _/_/_/ Venlo, The Netherlands
_/ _/ _/ _/
j...@oce.nl _/_/ _/_/_/ #include <std/disclaimer.h>
Kyle Jones
Jos Backus <j...@oce.nl> wrote:
> Hello Ryan,
>
> rcr...@site.gmu.edu (Ryan Cruse) wrote:
> >Will sendmail scale well for 10,000 users? 100,000 users? 1,000,000
> >users? How does the configureation change as it scales up and is
> >this an easy process?
> >
> >Example:
> >
> > Say I wanted to support a million users via pop3 mail and
> >use sendmail to send and recieve mail. How would I do this?
>
> I would dump sendmail and use qmail/qmail-pop3d.
I must ask, "Why?" I know of large installations using sendmail
to process millions of message per day. I know of no such qmail
installations. qmail is still considered in beta test by its
author. Seems risky to me. qmail needs more time on the test
bed before I would go live with it on a large installation.
Just one man's opinion.
D. J. Bernstein
Kyle Jones <kyle_...@wonderworks.com> wrote:
> I must ask, "Why?"
Remember the AOL outage? One host built up a backlog of 2000 messages
for AOL---but, because it was running qmail, it didn't even slow down.
Meanwhile, sendmail users were choking on much smaller queues.
> I know of large installations using sendmail
> to process millions of message per day.
Sure, like AOL---on thirty machines.
60000 messages per day on one host is not so impressive.
Not coincidentally, 70000 messages a day proved to be too much for
sendmail on the 48MB Pentium-100 at Red Hat Software. Now they're
letting qmail handle the load on a 16MB 486-66.
> qmail is still considered in beta test by its author.
Not any more.
---Dan
Brad Knowles
In article <1996Aug1700...@koobera.math.uic.edu>,
d...@koobera.math.uic.edu (D. J. Bernstein) wrote:
> > I know of large installations using sendmail
> > to process millions of message per day.
>
> Sure, like AOL---on thirty machines.
>
> 60000 messages per day on one host is not so impressive.
The only reason we have so many machines is to deal with very high
instantaneous loads generated by large junkmail attacks or large mailing
lists, not average loads over longer periods of time, like a day.
At times of high instantaneous loads, the machines used to be able to
clear at a rate in excess of 200K messages per day. And we recently made
some changes that lead me to believe that they'll now be able to clear at
a rate of approximately twice that. We put in these changes on what would
later turn into a day of nineteen hours downtime, and yet the system was
totally clean the next afternoon, having easily done two normal days worth
of traffic in less than one.
Sorry guy, qmail still just doesn't cut it.
--
Brad Knowles, MIME/PGP: br...@his.com
comp.mail.sendmail FAQ Maintainer <http://www.his.com/~brad/>
finger br...@his.com for my PGP Public Keys and Geek Code
The comp.mail.sendmail FAQ is at <http://www.his.com/~brad/sendmail/>
Brad Knowles
In article <4v5je7$r...@samba.rahul.net>, Rahul Dhesi <dh...@rahul.net> wrote:
> In all fairness, let it be noted that I did make available to the net a
> perl script called (coincidentally) 'qmail', a year or two ago. You can
> still get it at ftp://ftp.rahul.net/pub/dhesi/qmail . This is what I
> use to identify mail queued for hosts that are not accepting mail, and
> move it into a low-priority queue. Thus sendmail's main mail queue
> never gets clogged.
There's also Paul Pomes' re-mqueue program that was posted to
comp.mail.sendmail a while back, and several alternative programs have
been discussed as contributions to the distribution for version 8.8
sendmail. I suspect that there will be an effort to take the best of each
of them and create a combined program that is better than any of them.
> AOL's ability to accept incoming mail has been questionable ever since
> the beginning. I solved the problem around 1993. It was never an issue
> again.
Questionable in terms of what? Before I even got hired, I had people
from HP (who knew I was going to be working there) personally call me at
home to request that I upgrade them to version 8 sendmail, which didn't
happen as soon as I'd have liked but it did happen.
D. J. Bernstein
Brad Knowles <br...@his.com> wrote:
> And we recently made some changes that lead me to believe that they'll
> now be able to clear at a rate of approximately twice that.
A quick note to anyone sending mail through AOL: For several months,
Brad has been talking about putting his mail queues on RAM disks.
Draw your own conclusions.
> Sorry guy, qmail still just doesn't cut it.
Funny, Brad, how come you ran away when I challenged you to a speed test?
---Dan
Rahul Dhesi
In <1996Aug1700...@koobera.math.uic.edu>
d...@koobera.math.uic.edu (D. J. Bernstein) writes:
>Remember the AOL outage? One host built up a backlog of 2000 messages
>for AOL---but, because it was running qmail, it didn't even slow down.
>Meanwhile, sendmail users were choking on much smaller queues.
In all fairness, let it be noted that I did make available to the net a
perl script called (coincidentally) 'qmail', a year or two ago. You can
still get it at ftp://ftp.rahul.net/pub/dhesi/qmail . This is what I
use to identify mail queued for hosts that are not accepting mail, and
move it into a low-priority queue. Thus sendmail's main mail queue
never gets clogged.
AOL's ability to accept incoming mail has been questionable ever since
the beginning. I solved the problem around 1993. It was never an issue
again.
I have since then seen other scripts (none as well-written or
well-documented as mine, but that's my opinion) to do similar things.
And the basic sendmail manual talks about how to do things like 'mv
mqueue mqueue.old; mkdir mqueue' to handle a clogged mail queue. Given
that there are so many solutions to this particular problem, we should
no longer consider queue clogging a significant sendmail deficiency.
Resistance to queue clogging is still a point in favor of Dan's qmail,
but a bigger issue at some sites than at others.
--
Rahul Dhesi <dh...@rahul.net>
"please ignore Dhesi" -- Mark Crispin <m...@CAC.Washington.EDU>
Rahul Dhesi
>> AOL's ability to accept incoming mail has been questionable ever since
>> the beginning. I solved the problem around 1993. It was never an issue
>> again.
> Questionable in terms of what?
Too much detail would stray us from the topic of this newsgroup, but
briefly, there were periods of days during which AOL would not acccept
email. Connection timed out, connection reset by peer, host
unreachable, and other things.
Oh, BTW, at one time AOL was sending bounced mail with the reply address
showing MAILER-DAEMON, but they had no MAILER-DAEMON alias, so double
bounces triple bounces. They fixed when I notified them.
Jos Backus
kyle_...@wonderworks.com (Kyle Jones) wrote:
>Jos Backus <j...@oce.nl> wrote:
> > I would dump sendmail and use qmail/qmail-pop3d.
>
>I must ask, "Why?" I know of large installations using sendmail
>to process millions of message per day. I know of no such qmail
That hardly constitutes a reason not to consider moving to qmail. Remember
there was a time where sendmail didn't exist? qmail definitely has things
going for it, despite its being relatively new.
There are a number of reasons why one would choose qmail as a MTA, one of
these the partitioning of functionality for performance and security reasons.
Also, because of this, qmail scales better because the amount of memory
consumed as traffic increases is far less than in a typical sendmail
installation. qmail's processes are all lightweight compared to sendmail. On
top of that, qmail parallellizes often-executed operations to speed up
processing, and its retry scheduling is smarter in most cases.
Personally, I think it is very well-designed.
My two cents,
Jos
Michael Grubb
In article <1996Aug1700...@koobera.math.uic.edu>,
D. J. Bernstein <d...@koobera.math.uic.edu> wrote:
>Remember the AOL outage? One host built up a backlog of 2000 messages
>for AOL---but, because it was running qmail, it didn't even slow down.
>Meanwhile, sendmail users were choking on much smaller queues.
Proper use of sendmail 8.7's MinQueueAge option pretty much obviates this
concern. A machine running sendmail that "chokes" on a queue of < 2000
messages is (a) an under-sized PC, (b) running an out-of-date sendmail,
or (c) badly misconfigured.
-- M.
--
Michael Grubb <m...@duke.edu>
John Halleck
: In article <1996Aug1700...@koobera.math.uic.edu>,:
: > > I know of large installations using sendmail
: > > to process millions of message per day.
: > Sure, like AOL---on thirty machines.
: >
: > 60000 messages per day on one host is not so impressive.
We average (week long average) 3 messages a second. (259,200 or so a day)
(And that is averaging in a weekend.)
We go bursts of hours on end delivering 8 a second...
We are only using one machine for the tasks.
Kyle Jones
Jos Backus <j...@oce.nl> wrote:
> kyle_...@wonderworks.com (Kyle Jones) wrote:
> >Jos Backus <j...@oce.nl> wrote:
> > > I would dump sendmail and use qmail/qmail-pop3d.
> >
> > sendmail to process millions of message per day. I know of
> > no such qmail installations. [snip]
>
> That hardly constitutes a reason not to consider moving to
> qmail. Remember there was a time where sendmail didn't exist?
> qmail definitely has things going for it, despite its being
> relatively new.
I didn't say I wouldn't consider moving to qmail. I said qmail
has not yet been run at such a large installation. Therefore
there's almost no expertise out there to help you when the system
inevitably breaks down. sendmail has been around long enough
that there are plenty of people who know how to feed it and keep
it happy. qmail is mostly an unknown _at present_. Do you want
to learn as you go on a 10000 message/day system or a million
message per day system?
In the context of this discussion I don't fault qmail anything
but time. It was just released to the masses last week, for
Gog's sake.
Jos Backus
Hello Kyle,
kyle_...@wonderworks.com (Kyle Jones) wrote:
[snip]
>qmail is mostly an unknown _at present_. Do you want to learn as you go on a
>10000 message/day system or a million message per day system?
True, of course. I didn't mean to sound reproachful, I'm sorry if I did.
>In the context of this discussion I don't fault qmail anything
>but time. It was just released to the masses last week, for
>Gog's sake.
Yes, although it has been in beta for quite some time now at various sites.
Hopefully you'll like it as much as I do :)
Cheers,