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Total number of required tapes = round up ((2*F_GB + 12*I_GB + 11*D_GB) * CL / T_GB) + 1 = round
up ( (2*320 + 12*16 + 11*40) * 1 / 400 ) + 1 = round up ( 3.18 ) + 1 = 5 (tapes).
Tape planning: Example 2
Imagine the case with the following features:
full backup size is
F_GB
average size of incremental backups is
I_GB
average size of differential backups is
D_GB
compression level provides
CL
average reduction coefficient
selected tape rotation scheme is
Custom
with the following settings:
full backup - every 10 days
differential backup - every 2 days
incremental backup - every 1 day, every 6 hours
retention rules: delete backups older than 5 days
tape options are the following:
the
Use a separate tape set
option is selected
the
Always use a free tape: For each full backup
option is selected
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
tape size is
T_GB
.
The case defines the line of backups that consists of two sections. The figure below shows the
sections at the moment before the first backup will be deleted. In the figure the full, differential and
incremental backups are designated as orange, blue and green rectangles respectively.
At the moment some backups are deleted by the Cleanup task. Deletion of the outdated backups
painted in dark colors is postponed, as these backups are basic for the actual backups.
As an exact correlation between the tape size and backup's size is unknown, it is impossible to
determine number of the tapes that will be free after the deletion. So the calculation ignores this
probability.
Tape set 01 should contain (round up (( F_GB + 4*D_GB + 5*7*I_GB) * CL / T_GB)) tapes to store the
backups. Tape set 02 needs (round up (( F_GB + 1*D_GB + 7*I_GB) * CL / T_GB)) tapes. The sum of
the calculated values gives the total number of tapes required for the case.
4.1.3.9
What if
What if I have to move tapes with backups from one tape library to another?
1.
If both tape libraries are attached to the same machine with Acronis Backup & Recovery 10
Storage Node installed (i.e. the libraries are managed by the same storage node), the storage
