GFS Media Pools

The GFS (Grandfather-Father-Son) rotation scheme automatically creates three media pools-daily, weekly, and monthly-when you schedule a backup using this scheme. These pools are named according to the Media Pool Prefix you enter in the Schedule dialog box. Each media pool has its own Scratch Set and Save Set with a default retention period and minimum number of media to save.

The following are the GFS media pools and the formulas used to calculate their retention periods and number of media to save, when the default values are used:

Note: Arcserve Backup prevents you from using the underscore character ( _ ) and the hyphen character ( - ) when specifying Media Pool names.

• Daily pool-This pool holds the daily media. The default retention period is six days and the number of Save Set media is based on the number of daily media in the GFS rotation minus one [# of daily media -1].

  For example, if you are using the default GFS setup, where you preserve six daily media, the number of Save Set media in the GFS Daily Media Pool would be five: six daily media minus one. After six days have passed since the media was used [on the seventh day], it can be moved from the Save set to the Scratch set.

• Weekly pool-This pool holds the weekly media. The retention period equals the number of weekly media times seven, minus one [(# of weeklies * 7) - 1]. The number of save media is based on the number of weekly media in the GFS setup minus one [# of weekly media - 1].

  For example, if you are using the default GFS scheme, where you preserve five weekly media, 34 days would be the length of the retention period (5 times 7 minus 1). In the same example, four would be the number of save media in the GFS Media Pool (5 weekly media minus 1). After 34 days since the media was used (on the 35th day), it can be moved to the Scratch set, provided there are four (4) other media in the save set of the Weekly pool.

• Monthly pool-This pool holds the monthly media. The retention period equals the number of monthly media times 29 minus five [(# of monthlies * 29) - 5]. The number of save media is based on the number of monthly media in the GFS setup minus one [# of monthly media - 1].

  For example, if you are using the default GFS scheme, where you preserve 12 monthly media, 343 days would be the length of the retention period (12 times 29 minus 5). In the same example, 11 would be the number of save media in the GFS Media Pool (12 monthly media minus 1). After 343 days since the media has been used, it can be moved to the Scratch set, provided there are 11 media in the Save Set of the Monthly pool.

Note: If you preserve one media each month (12 monthly media), the retention period is 343 days, using the (12 *29)-5 formula, which takes into account months with differing number of days.

More information:

Rotation Schemes

Incremental and Differential Backup Operations

Use Rotation Scheme Options