There are many approaches that can be taken when backing up databases, and it is important to know your available options so that you can choose the backup approach that is best for your database protection requirements.
The most widely used database backup methods are Raw Database Backups or Full Exports, Incremental Backups, and Data Feeds.
Raw Backups or Full Export Database Backup
Many companies will keep full system images of their database servers as a form of backup. This is similar to mirroring, except that they keep several historical versions for roll-back purposes. It consists of ignoring the file system and copying every bit sequentially from one end of the hard drive to the other.
This approach is especially popular when it comes to virtualized environments, however it can lead to longer backup windows and significant storage costs. Â One major drawback to keeping raw system image backups is that the backup software does not keep track of how much disk space is used. For example, protecting a 2 TB server with only 20% used disk space would be very wasteful.
This approach requires the entire system to be locked down while the backups are occurring. If any transactions are processed while the data is being copied, it will result in a corrupted backup.
A full export is similar to a raw backup, except you only copy the data files associated with the database system. This is more efficient, since you don’t need to copy unused space. In the example listed above, this approach could be 5 times more efficient. Once again, a full database lock-down must take place during the backup process.
However, full exports can require more maintenance when it comes to a full recovery. The advantage of a raw system image is that it can quickly be loaded for easy recovery.
Raw Image Backups and Full Export are the fastest and simplest database backup methods.
Another disadvantage to these backup methods is that they do not allow time for systematic incremental backups. Some businesses try to work around this problem by maintaining separate transaction logs for disaster recovery, and re-loading these transactions after the most recent full backup backup has been restored. This loading process can take several days, and can create problems if not implemented properly.
File System Incremental Database Backup
The File System Incremental Backup method ignores the core database system and backs up all of the associated files or database exports, as it would with any other flat file.
This approach has the advantage of only backing up smaller chunks of the DB at a time while allowing the database to remain accessible. This method also allows the DB administrator to maintain stricter restore point objectives, reduce the need for more frequent full backups and help to streamline the point in time recovery.
However, it would be a mistake to rely on just any flat file backup solution to protect your database. Because of the complex relationships between the various database elements, synchronization issues may result if these incremental backups are not properly coordinated.
That’s why it’s important to have proper database backup tools at hand. At the very least, these incremental backups should be scheduled for times when the database is off-line, and no transactions are being processed.
Administrators can also implement incremental backups that are designed specifically for protecting and recovering logical data elements from databases, email servers and other enterprise systems. For administrators looking for granular recovery capabilities and incremental database backups, these tools would be best suited to these purposes.
Data Feeds Backup
Another — more complex — approach consists of maintaining data feeds to a storage manager. This is a more complex approach, and will be covered in more detail in future videos.
For more information on the leading database backup methodologies, we’ve included this short video.