Tape Rotation Strategies; Data Deduplication - HP StorageWorks D2D - Backup Systems User Manual

However, in order to ensure a high level of data integrity, the disks use RAID 6 protection. This reduces
the available capacity but ensures that, in the event of a disk failure in the device, there will be no
data loss.
The 12th disk is a hot spare disk. If a disk fails, the hot spare disk will immediately be used to replace
it. The RAID rebuild process occurs automatically. The failed disk should be replaced as soon as
possible.
Actual storage capacity is approximately:
• 9 TB for the HP D2D Backup System
• 18 TB for the HP D2D Backup System with Capacity Upgrade Kit
Data deduplication is enabled by default for each library device. This eliminates duplicate data from
backups and means that more histories of data can be stored and retained for longer on each library.
See also "Data
If you have the 12–disk model, it is possible to extend disk space by purchasing and installing the
12–disk Capacity Ugrade Kit. This doubles the storage capacity. Other options for creating space
are:
• Review your backup jobs to see if you can reduce the size of backup or retention time.
• Use the backup application job settings to overwrite or erase data.
• Export cartridges to physical tape.

Tape rotation strategies

Tape rotation strategies determine when backups are run, the number of cartridges that are required
and how they are reused. The HP D2D Backup System is a very flexible device that can easily be
incorporated into most tape rotation strategies. If your organization does not yet have a tape rotation
strategy in place, see for example configurations.

Data deduplication

Data deduplication compares blocks of data being written to the backup device with data blocks
previously stored on the device. If duplicate data is found, a pointer is established to the original
data, rather than storing the duplicate data sets. This removes, or "deduplicates," the redundant
blocks. The key part of this is that the data deduplication is being done at the block level and not at
the file level which reduces the volume of data stored significantly.
26 Before you start
deduplication" on page 26.