When you run or schedule an Exchange database backup job, you can specify whether to run a Full or Incremental backup. In a Full backup, the database files, checkpoint file and transaction logs are backed up. In an Incremental backup, only the transaction logs and checkpoint file are backed up after the first “seed” backup.
An Incremental backup takes less time to run than a Full backup. However, the time required to recover an Exchange database increases with the number of consecutive Incremental backups. To reduce the amount of time required for a recovery, we recommend performing a Full backup periodically. For example, you could schedule an Exchange backup job to run frequently with the Incremental backup type and periodically (e.g., once per week) with the Full backup type. As shown in the following table, the appropriate backup schedule can also depend on the Exchange database size and traffic.
|
Exchange database description |
Sample backup schedule |
|
Low traffic –
approximately 250 users, |
Full backup
every second Saturday night; |
|
Medium traffic
– approximately 1000 users, |
Full backup
every Saturday night; |
|
High traffic –
approximately 4000 users, |
Full backup every Wednesday and Saturday night; Incremental backup on other nights |
|
High traffic –
approximately 4000 users, |
Full backup
every Saturday night (which could be deferred to Sunday, if required);
|
You should always perform a Full backup after database repair, defragmentation or recovery. These processes significantly change Exchange databases.
Exchange maintenance can affect how much data is transferred during a Full backup. If you run daily maintenance on your Exchange server, the database will change considerably each day. When performing a Full backup, these changes are incorporated into the safeset and will result in longer Full backup times.
When scheduling backup jobs, consider the maintenance window. Backup jobs have priority over mailbox database maintenance. If a backup job runs at the same time as maintenance processes, maintenance will be put on hold until the backup is finished. A maintenance window usually provides enough time for maintenance processes to finish after an Incremental backup, but a Full backup could prevent maintenance processes from running.