Thanks a lot for the reply.
The clarifications to your queries are embedded -
Mehul Choksi <[EMAIL PROTECTED]> wrote:
> The purpose is to introduce qmail as an SMTP server in outbound email
> distribution system - just to send a million mails daily to subscribed
> users.
Do you mean send identical copies of one message to a million users, or send
one million unique emails, each to one user? The difference is enormous.
-----> It depends, normally in batches of 100,000 to 300,000 identical mails
prepared by an application to be sent to subscribers. Currently we use a
pool of sendmail servers (ordinary PIII 500 with 128MB RAM and IDE). We are
planning to migrate to QMAIL eventually if we find better performance.
* We tested the performance of the qmail by sending a few thousands mails to
> non-existent email-ids and to bounce back to another mail server.
Strangely
> enough, qmail just built up a huge queue, without even preprocessing.
qmail doesn't start new deliveries if there are messages waiting to be
preprocessed (in todo). If todo grows large, linear directory scan times
can
slow the system down significantly; Russell Nelson's big-todo patch might
help
here. Others have used various schemes, such as injecting X at a time,
pausing a minute or two in between injections to allow qmail to catch up
with
the todo contents, or trying first delivery with qmail-remote and only
queuing
the mail if that delivery fails, saving queue disk bandwidth.
* I will give big-todo a try and see if there is any improvement.
*
> Once the application stopped pumping to the Qmail server, it started
> processing and clearing queue, which took very long.
You may be running into a queue disk bandwidth limitation. What sort of
hardware are you using? Is the queue on a disk by itself? Is that disk a
15kRPM SCSI disk, sitting on its own U160 controller? Is that filesystem
mounted noatime? What filesystem are you using? What OS?
How are you logging? What does the system load reach while running your
injection? Have you read the section on large servers at www.qmail.org? Is
/var/log on a separate disk?
--> The server we are using is a very ordinary machine with PIII 500, 128MB
and an IDE on Red Hat Linux 6.0 with upgraded kernel. Logging is done
exactly the same way mentioned in the HOWTO. We will distribute the load of
SMTP using the LVS. The same test we ran on sendmail with the very similar
machine was acceptable - sendmail didn't build up a huge queue - it
processed all the mails. However, It was rather slow in accepting the
message though.
> Is it a normal behavior (since all the email addresses were non-existent)
or
> are we missing something somewhere? Concurrency is set to 120 for local
and
> remote.
It's not trivial, but a million unique mails a day can be handled by qmail
if
you set it up properly. We just need _way_ more information than you've
provided to start guessing at what your limiting factor(s) is.
--> Anyways, Thank you very much again for your time. I greatly appreciate
your suggestions.
Regards,
Mehul.
Charles
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Charles Cazabon <[EMAIL PROTECTED]>
GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/
Any opinions expressed are just that -- my opinions.
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