What Are the Benefits of Incremental Backups?

Incremental Backups is the best method to use in large scale databae(TB) and 24/7 DB, which will take more more resources of the system. This will make more performance issue for end users. To overcome this we can use Incremental backups/Differential backup.

Differential backup is very fast because SQL Server Database Engine tracks the changes that were made since the differential base was created.

More information :http://msdn.microsoft.com/en-us/library/ms175526.aspx

 

Writing incremental backups, although it does incur some processing time, will save considerably on elapsed backup time by writing less data. Tests performed by SoluTech Consulting indicate that using incremental backups to tape should be between three and four-and-a-half times faster than performing full backups to tape with tar, and one and a half times faster than a full SQL-BackTrack backup. The actual backup performance depends on many things: CPU speed, backup device speed and the amount of data changed in the database.

Recovery can be divided into the components of restoring the necessary files and recovering the database (which includes executing redo logs). I think ,the use of incremental backups may make the file restoration longer because you need to read both the full and incremental backup from the backup media. However, incremental backups taken frequently will reduce the amount of redo logs to play, resulting in a faster database recovery. So the actual performance impact will depend on how frequently you are performing incremental backups.

Magnetic tapes are not an infallible storage media. When you rely on many tapes full of archived redo logs to restore a database, you are vulnerable to a tape failure at any point in the chain. When you run incremental backups instead, you reduce the number of tapes on which you rely.

method:Advantages

• Files are easy to find - Since full backups include all data contained on a device, you don’t have to search through several media to find a file that you need to restore.

• There is always a current backup of your entire system on one media or media set - If you should need to restore your entire system, all of the most current information is located on the last full backup.

  • Files are easy to find - Restoring a system backed up with a differential strategy requires a maximum of two backups - the latest full backup and the latest differential backup. This is less time consuming than backup strategies that require the latest full backup and all incremental backups created since the full backup.

  • Less time required for backup and restore - Differential backups take less time to restore than full backups. Faster recovery is possible in disaster situations because you only need the latest full and differential backup media to fully restore a device.

• Better use of media - Only files that have changed since the last backup are included, so there is much less data storage space required.

• Less time required for backup - Incremental backups take much less time than full and differential backups to complete.

  • Restoring a system backed up with a working set strategy requires only the media containing the latest working set backup media and the media containing the most recent full backup.

  • You can perform a working set backup, restore the data to a new system, and be up and running faster than if you had to restore a full backup followed by all of the incremental or differential backups.

  • Working set backups take less time to run than full backups.

  method:Disadvantages

• Redundant backups - since most of the files on your file server rarely change, each full backup following the first is merely a copy of what has already been backed up. This requires more media.

• Full backups take longer to perform - Full backups can be time consuming, especially when you have other devices on the network that need to be backed up (e.g., agent workstations, remote servers).Redundant backups - All of the files created or modified since the last incremental backup are included; thus creating redundant backups.

Backups are spread across multiple media - Since multiple media is required in a disaster situation, this can cause recovery of a device to take longer. In addition, the media must be restored in the correct order to effectively bring the system up to date.The Last accessed in (x) days method is available only on platforms that support the last accessed date (Windows, NetWare, and UNIX). Working set backups will work as differential backups when selected for other platforms.