Re: Upgrade a mail server
On Fri, 15 Feb 2002 03:53, Alexander List wrote:
> > > This is becomming not scalable, and I want to start to use a mail
> > > server with auth based on sql, using MySQL for example. I am thinking
> > > in use a debian woody( I'll wait till woody becomes stable), with
> > > sendmail as smtp server, but I am not sure about the pop3 daemon I have
> > > to use.
>
> The problem I encountered is that if you want to have users with shell
> access, you need some mapping from the (whatever: LDAP, MySQL...)
> database to the uid/gid. That is needed for file permissions etc.
This is easy to do, libpam-ldap and libnss-ldap.
> So, if you want to have shell access, there's no way round /etc/passwd I
> guess. AFAIK there's some PAM modules for Novell that will auto-adduser if
> a user doesn't exist in the passwd database yet.
No. Just use LDAP for all of it. It's not difficult to setup and it works
well.
> If you want to have a sealed e-mail box, you could probably use
> Cyrus-IMAPd which also provides a pop server. I know that it is being used
> in several universities in Austria, with 10000 or more users. So I guess
> it scales quite well. Of course installing Cyrus for the first time is not
> as plug-and-pray as just throwing in your favourite pop3 server, but
> there's a script included that will convert the mailboxes to Cyrus'
> format.
Cyrus does not scale that well. Cyrus does not work on distributed servers,
it does not work well with NFS, and it does not have good support for
multiple domains.
Cyrus does work well if you want to do exactly what CMU does, have ~25K mail
boxes on a single machine in a single domain.
> > The best way of killing performance on a POP server is using
> > /var/spool/mail. Use Maildir storage and you'll get huge performance
> > gains.
>
> I can only support this opinion. I had a user from the publishing
> business, using Outlook on a Macintosh. His Inbox was ~280MB, the mail
> server machine had 256MB of RAM and he was coming in from abroad, so a
> quite unstable and slow network connection. It was a real nightmare,
> because he couldn't delete messages with Outlook, and ssh connections
> started to die because of the high packet loss...
A large company was doing some tests with my Postal program because of their
poor performance for mail serving. They had a Sun E450 machine with 4
UltraSPARC CPUs, 1.25G of RAM, and hardware RAID to support 1000 users, but
the performance still sucked because they used mbox.
With Maildir any Pentium class machine with 256M of RAM and a couple of IDE
drive could deliver better performance.
--
http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/ Postal SMTP/POP benchmark
http://www.coker.com.au/projects.html Projects I am working on
http://www.coker.com.au/~russell/ My home page
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