entryrdn index is used to associate DNs and RDNs with entries. It enables the server to efficiently perform subtree
moddn operations. The DN cache is used to cache the in-memory representation of the
entryrdn index to avoid expensive file I/O and transformation operations. For best performance, especially with but not limited to entry
move operations, set the DN cache to a size that enables Directory Server to cache all DNs in the database.
If a DN is not stored in the cache, Directory Server reads the DN from the
entryrdn.db index database file and converts the DNs from the on-disk format to the in-memory format. DNs that are stored in the cache enable the server to skip the disk I/O and conversion steps.
To set the size of the DN cache for the LDBM database to 20 MB:
Update the value in the Directory Server configuration:
# ldapmodify -D "cn=Directory Manager" -W -x
dn: cn=database_name,cn=ldbm database,cn=plugins,cn=config
Restart the Directory Server instance:
# systemctl restart dirsrv.target