Knowledgebase: Backup Strategies
Weekend full, weekday increment, alternating tapes
Posted by Sven Koester, Last modified by Sven Koester on 26 April 2018 15:52
Frequently we get asked how to implement a backup strategy that you have used to employ with your old backup product.

The requirements (which you are used to):
  • Run a weekly full backup, to be taken over the weekend.
  • Run incremental backups daily.
  • Use two sets of tapes, at least one of them stored off-site.
  • Ensure that no more than a single day-worth of data is lost.
  • Replace the tape in the library daily, and store it off-site
  • Use a finite and limited number of tapes.
  • Automatically handle the re-usage of tapes (re-labeling/recycling).
The idea behind this startegy is to be able to recover up to the last day's data, in case of a hazard on site.

How can this be achieved?

Create the following backup plan:
  • Saturday: Full backup
  • Sunday: Skip (so you have twice the time for the full backup)
  • Monday to Friday: Incremental Backup
In the backup plan, the following options must be set:
Backup Plan > Additional Options > Volume Use: Use new media
Backup Plan > Additional Options > Retail data for: 10 days

In the media pools used, the following option must be set:
Media Pool > Additional Option > Recycle policy: When expiration date is reached

Create two media pools, one for the Full backup and one for the Incrementals.
By employing a separate media pool for the full backups, it is easier to distinguish the full from the incremental tapes and it also allows you more flexibility in replacing the tapes in the library. By using a separate full backup pool, you can replace the full backup tape(s) against the other set at any time during the week, e.g. on Mondays, without having to worry about them being overwritten by the incremental run. With a single pool for both full and incremental backup, you would need to replace the tapes on the day before the full backup.

By configuring the plan this way, you will remove the tape last written with the increment every day and replace it with another one. This means, you need a total of 5 tapes (assuming your increment fits on one tape) in the Incremental pool.

 To easily identify the last written incremental tape we suggest the following handling:
  • Create a set of incremental tapes, one for each weekday (assuming that the incremental backup fits onto one tape).
  • On Monday of the first week, insert the Monday tape.
  • On Tuesday, take the Monday tape home and insert the Tuesday tape.
  • Proceed this way up to the end of the week.
  • Next week, place the Monday tape into the changer again.
  • Proceed as above.

In case of an upcoming holiday, place as many incremental tapes as are required into the library, to cover the duration of the holiday.
Should the holiday fall on a Monday, that is also not a problem, the full backup tapes can be exchanged a day later as well. Here the advantageous of using a different media pool for the full backup becomes obvious.

A look under the hood

PresSTORE is designed to perform backups fully automatically. Due to this fact, your backup would behave nearly the same in case all the tapes were permanently kept in the library. The only exception being that incremental tapes would be written up to full before the next tape would be used. PresSTORE would continue to perform a full backup alternating the two full backup sets, and would automatically recycle last week's incremental tapes as they are needed.
Replacing tapes in the library is not required, nor does PresSTORE require user intervention in deciding which tape to select. The purpose of replacing a tape is to enhance your security by allowing you to remove the tapes from the site.

Please also see the following white paper on progressive backups:

http://support.archiware.com/support/download/ProgressiveBackup.pdf

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Comments (1)
Sams
05 March 2011 22:30
This KB entry really should have a prominent link to your Progressive Backup Whitepaper.
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