I have an experiment, that may have too many moving parts to tease apart.

We're exploring migrating our LDAP server from a 32-bit OS to a 64-bit OS, and I've also explored the port to the mdb back end. My first shot at this does not show the performance the write-ups on MDB would have me expect.

If it matters, my old environment is a Dell R610 server, with 6G of RAM.

# uname -r 2.6.18-308.13.1.el5PAE # cat /etc/redhat-release CentOS release 5.8 (Final) # rpm -qf `which slapd` openldap-servers-2.3.43-25.el5_8.1

My ldapsearch invocations on this host take ~120 seconds.

I set up two Dell R610s, each with 12G or memory.

One environment uses the RPM produced by the LTB project, here named 'ltb':

root@ltb# uname -r 2.6.32-431.17.1.el6.x86_64 root@ltb# cat /etc/redhat-release CentOS release 6.5 (Final) root@ltb# rpm -qf /usr/local/openldap/libexec/slapd openldap-ltb-2.4.39-2.el6.x86_64

And the other uses the same OS, but uses CentOS's stock OpenLDAP RPM; here named 'stock':

root@stock# rpm -qf `which slapd` openldap-servers-2.4.23-34.el6_5.1.x86_64

I migrated a database of ~360k DNs, and underwent the cache tuning, following the suggestions here:

http://www.openldap.org/doc/admin24/tuning.html#Caching http://blog.monitor.us/2012/02/berkeley-db-performance-tuning/

And with those tunings, my ldapsearch command does outperform our old 32-but environment:

stock# time ldapsearch -x -w XXXXX -D "cn=manager,orgid=MyOrgID" -b orgid=MyOrgID dn | grep ^dn: | wc -l 3600071 real 0m27.147s user 0m19.216s sys 0m10.585s

However, my efforts to use the MDB backend yield slower responses, on the order of 175 seconds.

How I set up the MDB backend:

I copied my old slapd.conf over, and replaced my bdb backend with mdb settings.

- I set 'tool-threads' to 2 - I set 'maxsize' to 21474836480 [ 20G = 20 * ( 1024 * 1024 * 1024 ) ]

ltb# /usr/local/openldap/sbin/slaptest -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d config file testing succeeded ltb# chown -R ldap:ldap /etc/openldap/slapd.d

I was apparently able to import all 360k DNs without an error:

ltb# time setuidgid ldap /usr/local/openldap/sbin/slapadd \ -q -v -F /etc/openldap/slapd.d -b orgId=MyOrgID \ -l export_from_OLD.ldif >& log; echo $?

real 16m46.924s user 8m52.165s sys 3m44.859s 0

ltb# ls -ld data.mdb -rw------- 1 ldap ldap 21474836480 Jul 30 20:16 data.mdb ltb# du -c -h data.mdb 6.3G data.mdb 6.3G total

But, the same search looks worse here.

ltb# time ldapsearch -x -w XXXXX -D "cn=manager,orgid=MyOrgID" -b orgid=MyOrgID dn | grep ^dn: | wc -l 3600071 real 2m55.482s user 0m25.459s sys 0m23.948s

Both 64-bit hosts show no swapping, and minimal CPU load. Can anyone point out what I've missed?