Backup and Restore Overview

It is important for good data management to ensure that regular backups of the eLab database are made in the event of a system failure or data corruption. A successful backup operation adds a single backup set to the backup file. There are three types of backups:

Full - Creates a complete copy of the database.
Differential - Copies any changes made to the database since the last full backup.
Transaction Log - Copies a record of modifications performed to the database since the last backup.

You need to create at least one full backup in order to be able to create either of the other backup types. Creating frequent regular full backups can require a lot of disk space which is reduced by using differential backups. A combination of the occasional full backup, regular differential and more regular transaction log backups allows you to minimise the size of backups and reduce the potential for data loss.

The process of restoring an eLab database to the most recent backup depends on the type of that backup as follows:

Full - Restore the most recent full backup by itself.
Differential - Restore the most recent full backup then restore the most recent differential backup.
Transaction Log - Restore the most recent full backup, the most recent differential backup (if any), and all the transaction logs since that differential backup (or full backup if no differential backup exists).

To restore an eLab database to the most recent point you must first backup the transactions that have been committed but not backed up since the last backup - a tail log backup. If you are restoring to the point of a failure, the tail-log backup is the last backup of interest in the restoration process. If you cannot back up the tail of the log, you can restore the database only to the end of the last backup that was created before the failure.