ACRONIS Backup & Recovery 10 Advanced Server User's Guide download pdf (Page 154)

• GFS Example 3 (p. 158). The Use a separate tape set option is selected. All the Always use a free

tape options are selected. It requires 28 tapes in rotation.

These examples demonstrate how the number of tapes required for automated rotation depends on

the tape options. If a tape library does not have enough tapes for automated rotation, the Tasks

Need Interaction window will sometimes ask you to load a free tape into the library.

GFS Example 1

Suppose, the backup plan has the following tape options:

• the Use a separate tape set option is selected

• the Always use a free tape: For each full backup option is cleared

• the Always use a free tape: For each incremental backup option is cleared

• the Always use a free tape: For each differential backup option is cleared.

Imagine the first backup operation is scheduled on Friday 1st of January. On that day at 11:00 PM the

first full backup (320 Gb on the tape whose size is 400 Gb) is created. As the Use a separate tape set

option is selected, the currently mounted tape is ejected (if it is not a free tape). Then a free tape is

loaded especially for backing up the data. The tape is marked with number 01 in the figure below. In

accordance with the legend described in the Case to analyze (p. 152) section, the full data backup is

displayed as an orange rectangle in the figure.

The specified GFS backup scheme settings force the data to be backed up on Workdays only, so the

next backup is created at the same time (11:00 PM) on Monday 4th of January. This backup is an

incremental one (16 Gb) that is written onto the same tape 01, because the Always use a free tape:

For each incremental backup option is cleared. The backup is drawn as a green rectangle in the

figure.

The next three incremental backups are written onto tape 01 on 5th, 6th and 7th of January. As a

result the free space on the tape is only 16 Gb at the moment.

On 8th of January the data differential backup (40 Gb) is recorded onto the same tape 01, as the

Always use a free tape: For each differential backup option is cleared. However the tape reached the

end after the first 16 Gb of the backup is written. Then the tape is dismounted and ejected from the

drive into a slot by the loader. Further, a free tape is loaded into the same drive and mounted, and

then the backup (last 24 Gb) is continued onto the beginning of the new tape.

The next figure demonstrates the data backup archive at the moment. The differential backup is

drawn as a blue rectangle in the figure. Number 1 in the green rectangle marks the incremental

backup created on Monday of the 1st week of the year.

Then the following backups are written onto tape 02:

• four incremental and one differential backup on the second week

• four incremental and one differential backup on the third week

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ACRONIS Backup & Recovery 10 Advanced Server User's Guide Page 154