User`s guide

• the full size of the data to protect is approximately 320 GB

• the approximate size of daily changes of data is about 16 GB

• the approximate size of weekly changes of data is no more than 40 GB

• tape capacity is 400 GB.

Let’s analyze the results of a combination of GFS and ToH schemes with different tape options for the

case.

All the below analyzed examples are a simplistic approach to a real case, but provide you with a

general conception of backup distribution onto tapes.

Legend for the case example figures

Any daily/incremental backup (16 GB) is shown in the figures as a green rectangle: .

Weekly/differential backups (40 GB) are displayed as a blue rectangle:

Any full monthly backup (320 GB) is drawn in orange:

A whole tape (400 GB) is drawn as a gray rectangle:

Using the Grandfather-Father-Son tape rotation scheme

Tape rotation for the GFS backup scheme is substantially defined by the tape options specified for the

backup policy/plan to be created.

Assume the GFS settings are the following:

• Start backup at: 11:00:00 PM

• Back up on: Workdays

• Weekly/Monthly: Friday

• Keep backups: Daily: 2 weeks; Weekly: 2 months; Monthly: 1 year.

The main goal is to achieve full automation of tape rotation for these settings.

Keep in mind that a monthly backup is full, a weekly backup is differential, and a daily backup is

incremental in this implementation of the GFS scheme. The first backup is always full. So if the

backup policy/plan starts on Wednesday and full backups should be created on every fourth Friday,

on Wednesday the first backup will be full instead of an incremental one.

There are analyzed examples showing how the GFS scheme can be combined with different tape

options in the following sections:

• GFS Example 1 (p. 158). The Use a separate tape set option is selected. All the Always use a free

tape options are cleared. It requires 25 tapes in rotation.

• GFS Example 2 (p. 161). The Use a separate tape set option is selected. The Always use a free

tape: For each full backup option is selected. Other Always use a free tape options are cleared. It

requires 16 tapes in rotation.