Using Best Practices › Backup Recommendations › Database Level Backup Strategies

Database Level Backup Strategies

There are many factors that contribute to your backup strategy--backup window size, restore window size, server and storage hardware, the amount of available media, media retention time, network bandwidth, server load, and the size of your databases. Consequently, the backup strategy that you should use depends on your environment and physical hardware.

When determining a backup strategy, you must first assess the amount of time your organization has available each week for backing up your Exchange Server. When doing so, remember that the most time-consuming aspect of performing a restore is replaying the log files. Depending on how often you perform full backups, it can take several hours to replay log files on large servers during a restore because every transaction that has occurred since the last backup must be scanned. In addition, the speed at which transaction log replay occurs varies, depending on the type of transactions that must be replayed. Perform a test restore of your log files to get a more accurate estimate of how long it will take.

After you determine the size of your restore window, you must consider the affect that your environment and resources will have on your backup strategy:

• In an environment that has mission-critical data with minimal restore windows, you should perform full backups nightly (or during the hours your server is least active) and incremental backups at mid-day (or during a low production period during the day that is evenly spaced from your full backups).
• If media usage is a major factor in your backup strategy, either perform full backups daily or full alternating with differential backups daily.
• In an environment that has non mission-critical data with less aggressive restore windows, you should perform a full backup at least once a week and perform incremental or differential backups on the other days.

In Exchange Server 2007 CCR and Exchange Server 2010/2013 Database Availability Group (DAG) environments, you should use the default backup source to avoid affecting the performance of live databases. By default, the database is backed up from the replica, and the agent backs up from the active database only if no healthy replica is available. In Exchange Server 2010/2013 environments, if more than one replica for a database exists, the default order for replica selection is based on the database copy activation preference. The first copy is used first.

The following chart includes examples of a few backup strategies and their advantages and disadvantages. Although, for maximum protection, you should perform daily full and incremental backups, for maximum protection, you can customize your backup strategy to suit your organization’s needs. The only requirement is that you minimally perform daily backups on work days with a full backup once a week.

* Schedule full and incremental backups approximately 12 hours apart.