Chapter 14. Trimming the replication changelog

Procedure

1. 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"

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     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"

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     This command sets the maximum number of entries in the changelog to 100,000.

2. 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

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   This command sets the interval to 10 minutes (600 seconds).

Procedure

1. Optional: Display the size of the changelog:

   1. 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)

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      The name in parentheses is the back-end database that stores the data of the corresponding suffix.

   2. 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

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2. 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

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   If you do not see any specific attributes in the output, Directory Server uses their default values.

3. 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

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   Important

   For performance reasons, do not permanently use too short interval settings.

4. Wait until the time set in the --trim-interval parameter expires.

5. Compact the changelog to regain disk space:

   # dsconf -D "cn=Directory Manager" ldap://server.example.com backend compact-db --only-changelog

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6. 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

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