Terminology; Autoloaders; Backup Devices And Slots; Deduplication - HP StorageWorks D2D100 - Backup System User Manual

Terminology

Autoloaders

An autoloader is a backup device that has a single tape drive and multiple storage slots. (A library has
multiple tape drives, see "Libraries" on page 21.) Each storage slot contains a cartridge that can be
allocated to a specific backup task; for example, one cartridge can hold Monday's data, another can
hold Tuesday's data, and so on. In this way, backup applications are able to implement tape rotation
strategies that accommodate differing backup requirements for daily, weekly, monthly, yearly backups.

Backup devices and slots

Backup devices appear to the host as locally-attached tape devices, but physically, they use disk space on
the HP D2D Backup System which, as in tape terminology, is referred to as slots or cartridges.
The HP D2D supports the following emulation types: HP 1x8 G2 Autoloader, HP MSL Library (2x24), HP
MSL Library (4x24) and D2DBS Generic Library (48 slots). The default of 1x8 G2 Autoloader is correct
for many applications. (The number of drives is always restricted to 1, regardless of emulation type.)
See also "Devices
When you configure your HP D2D Backup System with a tape library, the drive emulation type that you
select determines the amount of physical disk space that is made available for each configured slot.
LTO-2 defaults to 200 GB, LTO-3 defaults to 400 GB and LTO-4 defaults to 800 GB. This is the equivalent
of a tape library with multiple slots, each containing a 200, 400 or 800 GB cartridge. Both tape
spanning and, more importantly, flexible tape rotation strategies are possible.
When you configure your HP D2D Backup System with a standalone tape drive, 200 GB of physical
disk space is made available for that tape drive. This is the equivalent of a permanently- mounted
200 GB tape cartridge, which cannot be unloaded. Tape spanning is impossible, so the data to be
backed up must not exceed 200 GB.

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. See
also "Data deduplication" on page 23.

Emulation types

HP D2D products emulate a range of physical Tape Autoloaders or Tape Libraries. Supported emulation
types are listed below:
• HP 1x8 G2 Autoloader
• HP MSL2024 Library
• HP MSL4048 Library
• HP D2DBS Library
If it is supported by your backup application, HP D2DBS Library is the preferred emulation type to be
used because it does not emulate any physical library types in existence and is clearly identifiable as a
D2D device. It is the most flexible emulation type available; however, backup application support varies
by software vendor. See also

Hosts on an Ethernet network

Each emulated backup device is uniquely mapped to an individual host; this is the network server or
PC that you wish to back up.
• The backup device appears to the host as a locally-attached tape autoloader or library.
• The backup device is accessed and managed from the backup software running on the host.
(Configuration)" on page 90.
"Emulation types for tape devices" on page 91.
D2D Backup System HP D2D2503
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