User`s guide

An incremental or differential backup created after disk defragmentation might be considerably larger than

usual because defragmentation changes file locations on the disk and the backup reflects these changes. It is

recommended that you re-create a full backup after disk defragmentation.

The following table summarizes the advantages and shortcomings of each backup type as they

appear based on common knowledge. In real life, these parameters depend on numerous factors

such as the amount, speed and pattern of data changes; the nature of the data, the physical

specifications of the devices, the backup/recovery options you set, to name a few. Practice is the best

guide to selecting the optimal backup scheme.

Parameter Full backup Differential backup Incremental backup

Storage space

Maximal Medium Minimal

Creation time

Maximal Medium Minimal

Recovery time

Minimal Medium Maximal

2.5. GFS backup scheme

This section covers implementation of the Grandfather-Father-Son (GFS) backup scheme in Acronis

Backup & Recovery 10.

With this backup scheme you are not allowed to back up more often than once a day. The scheme

enables you to mark out the daily, weekly and monthly cycles in your daily backup schedule and set

the retention periods for the daily, monthly and weekly backups. The daily backups are referred to as

“sons”; weekly backups are referred to as “fathers”; the longest lived monthly backups are called

“grandfathers”.

GFS as a tape rotation scheme

GFS was initially created and is often referred to as a tape rotation scheme. Tape rotation schemes,

as such, do not provide automation. They just determine:

• how many tapes you need to enable recovery with the desired resolution (time interval between

recovery points) and roll-back period

• which tapes you should overwrite with the forthcoming backup.

Tape rotation schemes enable you to get by with the minimal number of cartridges and not to be

buried in used tapes. A lot of Internet sources describe varieties of the GFS tape rotation scheme. You

are free to use any of the varieties when backing up to a locally attached tape device.

GFS by Acronis

With Acronis Backup & Recovery 10, you can easily set up a backup plan that will regularly back up

data and clean up the resulting archive according to the GFS scheme.

Create the backup plan as usual. For the backup destination, choose any storage device where

automatic cleanup can be performed, such as an HDD-based storage device or robotic tape library.

(Since the space freed on the tape after cleanup cannot be reused until all the tape becomes free,

take into account additional considerations when using GFS on a tape library (p. 157).)

The following is an explanation of the settings that are specific for the GFS backup scheme.