Hello,
From the Backup Exec point of view following information will help you.
Compression ratio is depend upon the type of data you are backing up.
Please refer to following technote.
Backups fail to get double the amount of the native capacity recorded to a
media, even when hardware compression is being utilized.
http://seer.support.veritas.com/docs/199542.htm
Above technote is applicable for Backup Exec 10.0 as well.
Following are the option for compression that can be selected and the
explanation.
-> Software
Select this option to use STACâ„¢ software data compression, which compresses
the data before it is sent to the storage device.
-> Hardware
Select this option to use hardware data compression (if the storage device
supports it). If the drive does not feature data compression the data is
backed up uncompressed.
-> Hardware
Select this option to use hardware data compression (if the storage device
supports it). If the drive does not feature hardware data compression, STAC
software compression is used.
-> None
Select this option to copy the data to the media in its original
form (uncompressed). Using some form of data compression can help expedite
backups and preserve storage media space. Hardware data compression should
not be used in environments where devices that support hardware compression
are used interchangeably with devices that do not have that functionality.
For example, if a drive that does not support hardware compression is added
to a cascaded drive pool which includes drives supporting the feature,
hardware compression is automatically disabled. You can manually re-enable
hardware compression on the drives that support it, but this results in
media inconsistency. If the drive that supports hardware compression fails,
the compressed media cannot be restored with the non-compression drive.
NOTE : If we do not receive your reply within two business days, this post would be marked assumed answered and would be moved to answered questions pool.
