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Re: OpenLDAP and BIG mail environments

On Thu, 12 Feb 2004, Quanah Gibson-Mount wrote:

> --On Thursday, February 12, 2004 12:32 AM -0600 Micah Anderson 
> <micah@riseup.net> wrote:
> >Quanah,
> >
> >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?
> In my testing, I found that increasing the threads past a certain point 
> *decreased* performance.  We found 20 to be the best number of threads for 
> our configuration.  Our cachesize is 5 times your, however.

Perhaps we would benefit from a larger cachesize and a reduced thread
count. It is really hard to guess what it should be, I wish there were
some decent guidelines available.

> >Does it make any sense to move our DB
> >files form the /var partition since they are probably all cached in
> >memory anyways?
> The main thing in 2.1 to think about, disk wise, is that your BDB log files 
> should be kept on a separate disk from your DB itself.  We have 2 drives, 
> and /db is the only partition on the second drive.  /var/log/bdb is located 
> on the first drive.

Is this because of the number of writes going into the BDB log files,
or purely for safety's sake (if the database crashes, then you have
the logs which you can reconstruct from), or both?

If part of this consideration is because of the large number of
writes, does it make sense to put these logs in a partition that
already has a high number of writes/sec (such as you have with
/var/log which I assume does a lot of writing, but little reading).

> One other question -- Do you have a local DNS caching service running on 
> your linux box?  We turn on reverse lookups in our slapd.conf, so we also 
> installed a local DNS cacher.

We do have a local dns caching service... we don't do reverse lookups
in our slapd.conf, but they happen in postfix frequently.

Thanks for your configuration advice, it helps to compare other's
setups and what they have been able to do with it.