Typical Vls Environments; Typical D2D Environments - HP 12000 Design Manual

Figure 2 HP Virtual Tape Library Product Range

Typical VLS Environments

In a typical enterprise backup environment, there are multiple application servers backing up data
to a shared tape library on the SAN. Each application server contains a remote backup agent that
sends the data from the application server over the SAN fabric to a tape drive in the tape library.
However, because backup over the SAN is single-threaded (a single host is backing up to a single
tape drive), the speed of any single backup can be limited. This is particularly true when the
environment has high-speed tape drives such as Ultrium 2 or Ultrium 3. The hosts simply cannot
keep the drives streaming at capacity.
NOTE: HP Ultrium drives will adjust the tape speed to match the data stream to prevent
"back-hitching." However, the tape drive is still not operating at optimal performance and cannot
share bandwidth with another backup job.
Enterprise data centers with slow SAN hosts in the environment may be unable to utilize the full
performance of high-speed tape drives. Also, shared tape libraries on the SAN can be difficult to
configure both in the hardware and in the data protection software.

Typical D2D Environments

In a typical entry-level or mid-range backup environment, the backup application is performing
LAN backups to a dedicated (non-shared) backup target such as a tape library connected to the
single backup server. Multiple instances of the backup application will generally each require their
own dedicated backup target. These environments may also be remote branch offices, each with
their own local backup application.
As with the VLS, the backup speed of a single host backing up to a single tape drive is normally
limited by the host (which cannot stream high-speed tape drives such as LTO), so currently tape
backups use multiplexing to interleave multiple hosts' backups together into a single tape drive
impacting restore performance. The addition of a D2D device to these environments allows
de-multiplexing of the backups so that restore performance is improved, the deduplication allows
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