Re: High load times with mdb

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

--On Tuesday, June 25, 2013 10:29 AM -0700 Bill MacAllister 
<whm@stanford.edu> wrote:

> With the release of Debian 7 (wheezy) I was rebuilding a couple test
> systems and was surprised to find that the load times I am seeing for
> populating the mdb database with slapd have gone up dramatically.  The
> load for a master server that was taking about 10 minutes just took
> 35 minutes.  The slave is worse.  A normal load time is 20 minutes
> and it is at 31 minutes now with an eta of about 2.5 hours.  These
> systems are using OpenLDAP 2.4.35.
>
> Here are some relevent bits from the configuration.
>
> dn: cn=config
> olcToolThreads: 2
>
> dn: olcDatabase={2}mdb,cn=config
> olcDbCheckpoint: 1024 5
> olcDbEnvFlags: writemap
> olcDbEnvFlags: nometasync
> olcDbNoSync: FALSE
> olcDbMaxSize: 85899345920
>
> The systems are Dell r610s with 16 gbyte of memory.  Our database
> is currently 3.2G on the master server.
>
> I have been loading wheezy/2.4.35 databases for weeks now in
> preparation upgrading the OS and installing the new version of OpenLDAP
> on our production servers.  This is the first time I have seen this.
>
> I fiddled with the hardware enough to the point I don't think it is
> a hardware problem.  There is not really much tuning to do with mdb
> and I would appreciate some suggestions for what to look at next.

If you've been doing multiple tests, you likely filled RAM.

I like to:

echo 3 > /proc/sys/vm/drop_caches

before doing a MDB load to empty RAM out.

--Quanah


--

Quanah Gibson-Mount
Sr. Member of Technical Staff
Zimbra, Inc
A Division of VMware, Inc.
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