Deduplication And Compression; Tape Rotation Example With Data Deduplication; Retention Policy; Data Parameters - HP StorageWorks D2D - Backup Systems User Manual

See "Configuring and using

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 110, 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.
Table 2 Data deduplication savings, example 1
1st daily full backup
1st daily incremental backup
2nd daily incremental backup
3rd daily incremental backup
4th daily incremental backup
5th daily incremental backup
2nd weekly full backup
28 Before you start
replication" on page 75 for more information about replication.
Data stored normally
500 GB
50 GB
50 GB
50 GB
50 GB
50 GB
500 GB
Data stored with deduplication
500 GB
5 GB
5 GB
5 GB
5 GB
5 GB
25 GB