ACRONIS Backup & Recovery 10 Advanced Workstation Podręcznik Użytkownika Pobierz pdf (Strona 341)

l evel s you sel ect. See the exampl e bel ow for details.

Example

Schedule parameters are set as follows

 Recur: Every 1 day

 Frequency: Once at 6 PM

Number of levels: 4

This is how the first 14 days (or 14 sessions) of this scheme's schedule look. Shaded numbers denote

backup levels.

1 2 3 4 5 6 7 8 9 10 11 12 13 14

4 1 2 1 3 1 2 1 4 1 2 1 3 1

Backups of different levels have different types:

 Last-level (in this case, level 4) backups are full;

 Backups of intermediate levels (2, 3) are differential;

 First-level (1) backups are incremental.

A cleanup mechanism ensures that only the most recent backups of each level are kept. Here is how

the archive looks on day 8, a day before creating a new full backup.

1 2 3 4 5 6 7 8

4 1 2 1 3 1 2 1

The scheme allows for efficient data storage: more backups accumulate toward the current time.

Having four backups, we could recover data as of today, yesterday, half a week, or a week ago.

Roll-back period

The number of days we can go back in the archive is different on different days. The minimum

number of days we are guaranteed to have is called the roll-back period.

The following table shows full backup and roll-back periods for schemes of various levels.

Num ber of

levels

Full backup

every

On different

days, can go

back

Roll-back

period

2 2 da ys 1 to 2 days 1 day

3 4 da ys 2 to 5 days 2 da ys

4 8 da ys 4 to 11 days 4 da ys

5 16 days 8 to 23 days 8 da ys

6 32 days 16 to 47 days 16 days

Adding a level doubles the full backup and roll-back periods.

To see why the number of recovery days varies, let us return to the previous example.

Here are the backups we have on day 12 (numbers in gray denote deleted backups).

1 2 ... 336 337 338 339 340 341 342 343 344 345 346 ... 368 369

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ACRONIS Backup & Recovery 10 Advanced Workstation Podręcznik Użytkownika Strona 341