Chapter 13. Trimming the replication changelog The Directory Server changelog manages a list of received and processed changes. It includes client changes and changes received from replication partners. By default, Directory Server trims the changelog entries that are older than seven day. However, you can configure: A maximum age of entries in the changelog in the nsslapd-changelogmaxage parameter. The total number of records in the changelog in the nsslapd-changelogmaxentries parameter. If you enabled at least one of these settings, Directory Server trims the changelog every five minutes by default ( nsslapd-changelogtrim-interval ). Even with the trimming settings enabled, any record and records subsequently created remain in the changelog until they are successfully replicated to all servers in the topology. If you remove the supplier from the topology as described in Removing a supplier from a replication topology , then Directory Server trims all the updates of this supplier from changelogs on other servers. 13.1. Configuring replication changelog trimming using the command line Directory Server trims the changelog entries that are older than seven days by default. However, you can configure the time after which Directory Server removes entries. You can also configure Directory Server to automatically remove entries if the number of entries exceeds a configured value. This section describes how to configure changelog trimming for the dc=example,dc=com suffix. Note Red Hat recommends setting a maximum age instead of a maximum number of entries. The maximum age should match the replication purge delay set in the nsDS5ReplicaPurgeDelay parameter in the cn=replica,cn=suffixDN,cn=mapping tree,cn=config entry. Perform this procedure on the supplier. Prerequisites You enabled replication for the dc=example,dc=com suffix. Procedure Configure change log trimming: To set a maximum age of changelog entries, enter: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-age " 4w " This command sets the maximum age to 4 weeks. The parameter supports the following units: s ( S ) for seconds m ( M ) for minutes h ( H ) for hours d ( D ) for days w ( W ) for weeks To set a maximum number of entries, enter: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-entries " 100000 " This command sets the maximum number of entries in the changelog to 100,000. By default, Directory Server trims the changelog every 5 minutes (300 seconds). To set a different interval, enter: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --trim-interval 600 This command sets the interval to 10 minutes (600 seconds). Verification Display the changelog settings of the suffix: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication get-changelog --suffix " dc=example,dc=com " dn: cn=changelog, cn=userroot ,cn=ldbm database,cn=plugins,cn=config cn: changelog nsslapd-changelogmaxage: 4w nsslapd-changelogtrim-interval: 600 ... The command only displays the parameters that are different to their default. 13.2. Manually reducing the size of a large changelog In certain situations, such as if replication changelog trimming was not enabled, the changelog can grow to an excessively large size. To fix this, you can reduce the changelog size manually. This procedure describes how to trim the changelog of the dc=example,dc=com suffix. Perform this procedure on the supplier. Prerequisites You enabled replication for the dc=example,dc=com suffix. Procedure Optional: Display the size of the changelog: Identify the back-end database of the dc=example,dc=com suffix: # dsconf -D " cn=Directory Manager " ldap://server.example.com backend suffix list dc=example,dc=com ( userroot ) The name in parentheses is the back-end database that stores the data of the corresponding suffix. Display the size of the changelog file of the userroot backend: # ls -lh /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db -rw-------. 1 dirsrv dirsrv 517M Jul 5 12:58 /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db To be able to reset the parameters after reducing the changelog size, display and note the current values of the corresponding parameters: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication get-changelog --suffix " dc=example,dc=com " dn: cn=changelog, cn=userroot ,cn=ldbm database,cn=plugins,cn=config cn: changelog nsslapd-changelogmaxage: 4w nsslapd-changelogtrim-interval: 300 If you do not see any specific attributes in the output, Directory Server uses their default values. Temporarily, reduce trimming-related parameters: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-age " 300s " --max-entries 500 --trim-interval 60 Important For performance reasons, do not permanently use too short interval settings. Wait until the time set in the --trim-interval parameter expires. Compact the changelog to regain disk space: # dsconf -D " cn=Directory Manager " ldap://server.example.com backend compact-db --only-changelog Reset the changelog parameters to the values they had before you temporarily reduced them: # dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-age " 4w " --trim-interval 300 Verification Display the size of the changelog: # ls -lh /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db -rw-------. 1 dirsrv dirsrv 12M Jul 5 12:58 /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db

Commands:
dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-age " 4w "
dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-entries " 100000 "
dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --trim-interval 600
dsconf -D " cn=Directory Manager " ldap://server.example.com replication get-changelog --suffix " dc=example,dc=com " dn: cn=changelog, cn=userroot ,cn=ldbm database,cn=plugins,cn=config cn: changelog nsslapd-changelogmaxage: 4w nsslapd-changelogtrim-interval: 600
dsconf -D " cn=Directory Manager " ldap://server.example.com backend suffix list dc=example,dc=com ( userroot )
ls -lh /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db -rw-------. 1 dirsrv dirsrv 517M Jul 5 12:58 /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db
dsconf -D " cn=Directory Manager " ldap://server.example.com replication get-changelog --suffix " dc=example,dc=com " dn: cn=changelog, cn=userroot ,cn=ldbm database,cn=plugins,cn=config cn: changelog nsslapd-changelogmaxage: 4w nsslapd-changelogtrim-interval: 300
dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-age " 300s " --max-entries 500 --trim-interval 60
dsconf -D " cn=Directory Manager " ldap://server.example.com backend compact-db --only-changelog
dsconf -D " cn=Directory Manager " ldap://server.example.com replication set-changelog --suffix " dc=example,dc=com " --max-age " 4w " --trim-interval 300
ls -lh /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db -rw-------. 1 dirsrv dirsrv 12M Jul 5 12:58 /var/lib/dirsrv/slapd- instance_name /db/ userroot /replication_changelog.db