RE: How to improve performance with MDB backend?

[Chris Card <ctcard@hotmail.com>]

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> Date: Thu, 18 Apr 2013 08:50:23 -0700
> From: quanah@zimbra.com
> To: ctcard@hotmail.com; openldap-technical@openldap.org
> Subject: RE: How to improve performance with MDB backend?
>
> --On Thursday, April 18, 2013 3:29 PM +0000 Chris Card <ctcard@hotmail.com>
> wrote:
>
> >> Did you make the changes to the DB flags for MDB that I noted the other
> >> day? For me, MDB writes are a minimum of 65 times faster than writes with
> >> BDB/HDB, even when BDB/HDB use an SHM key.
> > Yes. I have these values in my mdb configuration:
> > olcDbEnvFlags: writemap
> > olcDbEnvFlags: nometasync
> >
> > I think these setting may have helped to speed up slapadd, but not
> > ldapmodify.
>
> I'm specifically talking about ldapmodify actually. ;)
>
> <http://wiki.zimbra.com/wiki/OpenLDAP_MDB_vs_HDB_performance>

Maybe MDB performance relative to BDB degrades as the database get bigger. 
>From your wiki page: "This particular client has 25,208 entries in their LDAP database".
My test database has over 3 million entries (production has nearly 7 million), which take about 20 minutes to slapadd into MDB initially.
My machine has 128 Gb RAM and the MDB db size is 429496729600, so slapd can't map the whole db file into RAM.

Chris