Deduplication And Compression; Tape Rotation Example With Data Deduplication; Retention Policy; Data Parameters - HP StorageWorks D2D100 - Backup System User Manual

• 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

Deduplication and compression

Compression is applied as part of deduplication. You can expect 1.6:1 compression even on the first
backup where no (or only a small amount of) deduplication can occur. If you disable deduplication, see
"Devices (Configuration)" on page 69, no compression is applied to data on that device.

Tape rotation example with data deduplication

The two most significant 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 file 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 files)

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 offline.
• 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
figures are used to generate the graph shown after the table.
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