HP D2D100, Руководство пользователя

Страница: 23 / 176

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 fi le level
which reduces the volume of data stored signi fi cantly.
Figure 5 Data stored after deduplication
In actual practice, data deduplication is often used in conjunction with other forms of data reduction such
as conventional data compression to offer the greatest reduction in data volume stored.
Technology types
There are a number of technology types that use different deduplication algorithms. The HP D2D applies
on-the- fl y deduplication to chunks of backup data as they are written to the unit. It does not matter which
application was used to create the backup. For further information about deduplication techniques and
relative bene fi ts, refer to the white papers at http://www.hp.com .
Data deduplication and the HP D2D
Data deduplication is applied per library device. When you con fi gure the library, it defaults to
deduplication enabled. If you disable it, deduplication cannot be selectively applied to any data on the
library device. Compression is also disabled, if deduplication is disabled.
A library is associated with a host server and deduplication allows a greater amount of backup history
to be stored for that host. A larger number of full backups can be achieved, which makes possible a
rotation strategy with a longer retention history. It does not increase the number of host servers that
may be connected. The deduplication factor that has been applied to a library device is calculated
and displayed on the Web Interface. This fi gure is dynamic, it updates automatically as more data is
written to the library.
Bene fi ts of HP D2D deduplication
The main bene fi t is that it is possible to store more data and retain data for longer on each cartridge
within a library. The host using the library device has access to a greater depth of historical data
that would otherwise have been archived of fl ine.
Deduplication:
• Provides ef fi cient use of storage capacity by eliminating duplicate data
D2D Backup System HP D2D2503
23