19. Maintenance
System Administration is all about maintenance, so it is only fair that we discuss how to correctly maintain an OpenLDAP deployment.
19.1. Directory Backups
Backup strategies largely depend on the amount of change in the database and how much of that change an administrator might be willing to lose in a catastrophic failure. There are two basic methods that can be used:
1. Backup the LMDB database itself
The LMDB database can be copied live using the mdb_copy command. If the database is a sparse file via the use of the "writemap" environment flag, the resulting copy will be the actual size of the database rather than a sparse copy.
2. Periodically run slapcat and back up the LDIF file:
Slapcat can be run while slapd is active. However, one runs the risk of an inconsistent database- not from the point of slapd, but from the point of the applications using LDAP. For example, if a provisioning application performed tasks that consisted of several LDAP operations, and the slapcat took place concurrently with those operations, then there might be inconsistencies in the LDAP database from the point of view of that provisioning application and applications that depended on it. One must, therefore, be convinced something like that won't happen. One way to do that would be to put the database in read-only mode while performing the slapcat. The other disadvantage of this approach is that the generated LDIF files can be rather large and the accumulation of the day's backups could add up to a substantial amount of space.
You can use slapcat(8) to generate an LDIF file for each of your slapd(8) back-mdb databases.
slapcat -f slapd.conf -b "dc=example,dc=com"
For back-mdb this command may be ran while slapd(8) is running.
19.2. Checkpointing
Setting a checkpoint is only necessary when back-mdb has the dbnosync flag set. Otherwise it has no effect. With back-mdb the kbyte option is not implemented, meaning it will only run a checkpoint based on the elapsed amount of minutes flag.
19.3. Migration
If upgrading, please consult Upgrading from 2.5.x first to see if you need to make changes to your configuration as part of the upgrade.
After that, the simplest steps needed to migrate between versions or upgrade, depending on your deployment type are:
- Stop the current server when convenient
- slapcat the current data out
- Clear out the current data directory (/usr/local/var/openldap-data/)
- Perform the software upgrades
- Perform any configuration upgrades required
- slapadd the exported data back into the directory
- Start the server
Obviously this doesn't cater for any complicated deployments with N-Way Multi-Provider, but following the above sections and using either commercial support or community support should help. Also check the Troubleshooting section.