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?