Acronis Backup & Recovery 10 Advanced Workstation TIDLBPDES5 Manuale Utente

Codici prodotto
TIDLBPDES5
Pagina di 360
 
• 
differential backups on all intermediate levels (B, C and D for five-level pattern) 
• 
the pattern starts with a full backup since the very first backup cannot be incremental 
• 
the scheme forces every backup level to keep only the most recent backup, other backups from 
the level have to be deleted; however backup deletion is postponed in cases where the backup is 
a base for another incremental or differential one 
• 
an old backup on a level is kept until a new backup has been successfully created on the level. 
The table shows the pattern for the five-level backup scheme. The pattern consists of 16 sessions. 
 
As a result of using incremental and differential backups the situation may arise when an old backup 
deletion must be postponed as it still is a base for other backups. The table below indicates the case 
when deletion of full backup (E) created at session 1 is postponed at session 17 until session 25 
because the differential backup (D) created at session 9 is still actual. In the table all cells with deleted 
backups are grayed out: 
 
Differential backup (D) created at session 9 will be deleted at session 25 after creation of a new 
differential backup is completed. This way, a backup archive created in accordance with the Tower of 
Hanoi scheme by Acronis sometimes includes up to two additional backups over the classical 
implementation of the scheme. 
For information about using Tower of Hanoi for tape libraries, see Using the Tower of Hanoi tape 
rotation scheme (p. 147). 
 
2.7. Retention rules 
The backups produced by a backup plan make an archive. The two retention rules described in this 
section enable you to limit the archive size and set the lifetime (retention period) of the backups. 
1. Delete backups older than 
This  is  a  time  interval  counted  back  from  the  moment when the retention rules are applied. Every 
time a retention rule is applied, the program calculates the date and time in the past corresponding 
38
 
Copyright © Acronis, Inc., 2000-2009