OpenLDAP Performance Tuning 6.0

 - This article is a Work in Progress, and may be unfinished or missing sections.

Zimbra OpenLDAP Server

Currently only one master LDAP server can be set up; this server is authoritative for user information, server configuration, etc. Replica LDAP servers can be defined to improve performance and to reduce the load on the master server. All updates are made to the master server and these updates are copied to the replica servers.

Upcoming on radar: RFE 27872 - Support multi-master LDAP deployment

For best performance, the following settings should be modified. These settings apply to both the master LDAP server and the replica servers.

• Set the threads count to an appropriate level. The ZCS default is 8, which is fine for 1 or 2 CPU servers. The general rule of thumb is 4 threads for every real core.

zmlocalconfig -e ldap_common_threads=8

• Set the toolthreads count to an appropriate level. The ZCS default is 1. It should be set to the number of real cores you have available. The purpose of the toolthreads setting is to decrease the amount of time it takes to slapadd a database.

zmlocalconfig -e ldap_common_toolthreads=4

• Change the entry cachesize for the primary database. The number set should be the number of configured active accounts and the number of configured active domains. The default is 10000.

zmlocalconfig -e ldap_db_cachesize=50000

• Set idlcachesize for the primary database. The number set should be the same as the cachesize setting.

zmlocalconfig -e ldap_db_idlcachesize=50000

• Change the dn entry cachseize for the primary database. It is highly recommended to leave it at the default value of zero, which means an unlimited DN cache. If it is set to a non-zero value, it should be no less than two times the entry cache.

zmlocalconfig -e ldap_db_dncachesize=0

If you have more than 100 domains, we suggest adjusting the following local config setting:

• ldap_cache_domain_maxsize. This sets the cache of the number of domains in the server. The default is 100. If more than 100 domains are configured, you should adjust this to the lower of the number of domains you have configured and 30,000. For example, with 45,000 domains, set as this to 30000.

# Apply this to all mailbox servers!
zmlocalconfig -e ldap_cache_domain_maxsize=30000