HP D2D100, Руководство пользователя

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• Reduces disk expenditures by reducing storage space required. You can get more backups for each
host on the same size of storage (HP D2D device)
• Prolongs disk data retention periods
• Reduces the volume of data that must be sent across a WAN for remote backups, replication, and
disaster recovery – reducing both risk and operational costs
See “ Con fi guring and using replication ” on page 59 for more information about replication.
Deduplication and compression
Compression is applied as part of deduplication. You can expect 1.6:1 compression even on the fi rst
backup where no (or only a small amount of) deduplication can occur. If you disable deduplication, see
“ Devices (Con fi guration) ” on page 90, no compression is applied to data on that device.
Tape rotation example with data deduplication
The two most signi fi cant factors affecting the deduplication ratio for backup are:
• How long do you retain the data?
• How much data changes between backups?
The following example shows projected savings for a 1 TB fi le server backup.
Retention policy
• 1 week, daily incrementals (5)
• 6 months, weekly fulls (25)
Data parameters
• Data compression rate = 2:1
• Daily change rate = 1% (10% of data in 10% of fi les)
Typical savings
The following table illustrates a reduction of approximately 11:1 in data stored. In practice, assuming
1.25 TB is available for backup for this library, this means:
• Without data deduplication: only two weeks of data retention is possible before it is necessary to
archive data of fl ine.
• With data deduplication: even after six months less than 1.25 TB of disk space has been used.
The following table illustrates how this affects the space required to store the data over 25 weeks. The
fi gures are used to generate the graph shown after the table.
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Before you start