Further Information; Compression; Archiving To Tape - HP StorageWorks D2D100 - Backup System User Manual

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Figure 40 Archiving to tape

Further information

It is not possible to describe how to carry out this operation because it is controlled solely from the backup
application and different applications operate in different ways. HP provides a number of white papers
that describe how to use this function with specific applications; see http://www.hp.com/support. Or
refer to the documentation that was supplied with your backup application.

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.
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Copy using a tape drive attached to the host
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Backup Data
Copy Data
HP StorageWorks D2D
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Tape Drive