High load times with mdb

[Bill MacAllister <whm@stanford.edu>]

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.

Bill

--

Bill MacAllister
Infrastructure Delivery Group, Stanford University