Re: slapd does not answer in time

[Quanah Gibson-Mount <quanah@zimbra.com>]

--On Thursday, February 21, 2008 3:19 PM +0100 Hans Moser 
<hans.moser@ofd-sth.niedersachsen.de> wrote:

> Hi!
>
> I have a 4 cpu machine with SLES 9 and OpenLDAP 2.3.35.
> This is master to about 65 slaves via syncreplication.

Why do you have 65 slaves?  I've yet to really see a need for more than 3-4 
slaves unless one has world-wide distributed offices or the like.  I would 
note the following:

(a) there have been a number of significant fixes to sync replication since 
2.3.35
(b) syncrepl is highly intensive.  delta-syncrepl is not so intensive for 
ongoing writes
(c) Using a full refresh instead of doing a slapcat of the master/slapadd 
of the slave (or slapcat of an existing slave to add to a slave) is highly 
intensive
(d) You make no mention of any tuning you may (or may not) have done, via 
the DB_CONFIG file for BDB, or the cachesize, idlcachesize, threads, or 
indexing for slapd, all of which could directly impact the performance of 
the master.
(e) I generally advise a setup where the master is isolated to only taking 
writes(*), while letting replicas handle the reads.

(*) - Things that need a guaranteed response should use the master.

--Quanah


--

Quanah Gibson-Mount
Principal Software Engineer
Zimbra, Inc
--------------------
Zimbra ::  the leader in open source messaging and collaboration