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Re: OpenLDAP and BIG mail environments


Can you give some details of your slapd.conf and any tunables you've
done in your ldap.conf or anything you've done to tune your BDB? I am
currently in a situation where we are running about 6,000 users, doing
as described (postfix, courier imap/pop, maildrop, openldap 2.1.25,
debian stable, kernel 2.4.24, Sleepycat Berkeley DB 4.2.52, AMD 2000
MP+ processors and one gig of RAM) and we are experiencing some scale
issues (high loads due to slapd processes in sleep state) and are
trying to track down the problem.

I'm considering the realtime scheduler patch
(http://rtsched.sourceforge.net/) because running strace on some of
the sleeping slapd processes show that it is using the real time
signal code quite heavily. I have also heard that there is a O(1)
scheduler patch for 2.4 that makes the 2.4 scheduler act like the 2.6
one, which can drastically improve things.

We've got schemacheck off and our threads increased to 64, cachesize
2000 and not much else that we've been tweaking, you can see our
graphs culled from the monitor stuff here:

I'm very interested in ways people have optimized things, because I
feel like there is a lot more optimization that we can do, but I am
having trouble finding info on this. What should our next steps be,
what should we be planning for? Does it make any sense to move our DB
files form the /var partition since they are probably all cached in
memory anyways?

... I'm glad this topic came up, because I was going to post something


On Wed, 11 Feb 2004, Quanah Gibson-Mount wrote:

> --On Wednesday, February 11, 2004 2:00 PM -0800 James Courtney 
> <Jcourtney@inphonic.com> wrote:
> >Background:
> >We're currently supporting 20,000 users on a Mirapoint mail system backed
> >by a server running OpenLDAP 2.1.25 with DB 4.2.52 behind.  Things are
> >currently running quite well but we're rearchitecting our system and
> >we're told that we may be brining in 20,000+ users a month on a feature
> >limited version of our product which only supports mail (voice mail to be
> >specific).  Our product stores messages (voice mail, email, fax) in our
> >email server which we're building anew ourselves using the above
> >mentioned components.  Clearly the mail server and LDAP in that case will
> >get a good workout...
> Hi Jamey,
> We have approximately 50k accounts that get mail delivered to on a daily 
> basis.  We use openldap as our backend for maildrop lookups.  There are 3 
> OpenLDAP servers dedicated to this purpose.  We are using sendmail right 
> now instead of postfix (but are in the process of upgrading).  Our servers 
> have been able to handle the daily load without problem.  I will also note 
> that about 50% of our email is spam, so that is on top of the 50k actual 
> accounts that exist.  We get over 1 million queries a day per server (so 
> over 3 million queries a day) last I checked.  The OpenLDAP servers handle 
> this without complaint.
> --Quanah
> --
> Quanah Gibson-Mount
> Principal Software Developer
> ITSS/TSS/Computing Systems
> ITSS/TSS/Infrastructure Operations
> Stanford University
> GnuPG Public Key: http://www.stanford.edu/~quanah/pgp.html