Disadvantages Of Export; Compression; Cartridge Import - HP StorageWorks D2D - Backup Systems User Manual

is required, the backup application will ask for the cartridge to be re-imported into the HP D2D before
it can be used for restore. Exported cartridges may also be used for disaster recovery, as with copied
cartridges.

Disadvantages of Export

1.
Restores may take longer if a physical cartridge is required for the restore.
2.
Backup applications may require the exported cartridge for the next job in their rotation scheme.

Compression

When you are moving data from the HP D2D to physical tape, it is important to be aware that the
cartridge maximum size is the native size (without compression). HP StorageWorks tape drives apply
hardware compression, therefore, the data from the HP D2D Backup System is likely to require less
space on a physical tape cartridge. When moving data to a physical cartridge for off-site storage,
there is no need for concern if the data seems to utilize less space.
The capacity quoted for physical media assumes that the tape drive will be able to compress your
data and reduce the file sizes by 50%, but this can be achieved only if your data is not already
compressed. For example, JPEG pictures, movies, music or ZIP files, are already in compressed
formats: spreadsheets, text files, high-resolution graphics are not. Most users have a mixture of
compressed and uncompressed data and seldom achieve 50% compression.
Some users may choose to enable software compression from their backup application to increase
the storage space available to the backup application, but this can make backup jobs slower to run.
However, once software compression has been applied, the data is not further compressed when it
is exported to a physical tape directly attached to the HP D2D Backup System. This ensures that the
user knows exactly how much physical cartridge space is required for export or copy.

Cartridge import

The Web interface on the HP D2D is used to Import cartridge data from the attached tape storage
device to the mail slot on the HP D2D Backup System. The backup application on the host is used to
move the data from the mail slot back into one of the library slots.
152 Using Tape Attach