Chapter 9. Tuning transaction logging

At regular intervals, Directory Server writes the transactions logged logged in the transaction log to the database files and logs a checkpoint entry in the database transaction log. By indicating which changes have already been written to the database, checkpoint entries indicate where to begin recovery from the transaction log, thus speeding up the recovery process.

By default, Directory Server sends a checkpoint entry to the database transaction log every 60 seconds. Increasing the checkpoint interval can increase the performance of directory write operations. However, it can also increase the amount of time required to recover directory databases after a disorderly shutdown and require more disk space due to large database transaction log files.

At regular intervals, Directory Server writes the transactions logged logged in the transaction log to the database files and logs a checkpoint entry in the database transaction log. By indicating which changes have already been written to the database, checkpoint entries indicate where to begin recovery from the transaction log, thus speeding up the recovery process.

By default, Directory Server sends a checkpoint entry to the database transaction log every 60 seconds. Increasing the checkpoint interval can increase the performance of directory write operations. However, it can also increase the amount of time required to recover directory databases after a disorderly shutdown and require more disk space due to large database transaction log files.

Durable transaction logging means that each LDAP update operation, comprised of a sequence of database operations in a transaction, is physically written to disk. Even though each LDAP operation can be comprised of multiple database updates, each LDAP operation is treated as a single database transaction. Each LDAP operation is both atomic and durable.

When you disable durable transaction logging, Directory Server writes every directory database operation to the database transaction log file but it may not be physically written to disk immediately. If a directory change was written to the logical database transaction log file but not physically written to disk at the time of a system crash, the change cannot be recovered. When durable transactions are disabled, the recovered database is consistent but does not reflect the results of any LDAP write operations that completed just before the system crash.

Note that you cannot change the nsslapd-db-durable-transaction parameter if Directory Server is running.