Automated Media Pools white paper for ESL G3 (QN998-96026, June 2011)

Traditional solutions
Traditionally there have been two ways to implement
tape library partitioning; either using dedicated
sharing software, or using the hardware interface to
create a set of fixed partitions. Unfortunately, both of
these solutions have drawbacks.
Dedicated sharing software
The advantage of using dedicated sharing software is
that it creates a large scratch media pool, and offers
the ability to scale very easily as capacity grows.
However, these benefits are frequently outweighed by
the need to:
• Purchase and maintain a server to run the sharing
software
• Configure the media pools or server access control
lists in the sharing software
• Manage multiple layers of configuration –
hardware and software
• Work through greater complexity if the backup fails
• And finally, dedicated sharing software typically
locks you in to one library vendor
Fixed partitions
Fixed partitions, on the other hand, won’t require you
to make an extra investment in hardware or software,
and they don’t increase the layers between your
backup application and the library. Administrators
can assign an ISV per partition or customer; thus,
preventing co-mingling of customer data; the library
firmware protects media in one virtual library against
use by an ISV in another partition.
However, fixed partitions are by definition,
more difficult to change. They often require a
reconfiguration of the ISV software to respond to size
fluctuations and this has associated time delays and
resource implications.
HP Solution: Automated Media Pool
(AMP)
HP ESL G3 Tape Libraries take partitioning to the next
level, building on the benefits of fixed partitioning
with one important difference – the ability to flexibly
change partition sizes.
The Automated Media Pool (AMP) feature
is an intelligent way to expand and shrink
virtual library capacity via the familiar
concept of ‘Thin Provisioning’.
In the conventional storage provisioning model,
storage space is allocated beyond current needs,
in anticipation of growing need and increased data
complexity. As a result, the utilization rate is low.
Large amounts of storage space are paid for but may
never be used. In thin provisioning, these problems
are eliminated while keeping overhead low.
Firstly, administrators allocate normal partitions
consisting of slots, drives, and mail slots to meet
current backup requirements. Then, a special partition
consisting purely of slots is configured to act as a
backing store. The slots in this partition are used as
a flexible media pool should a dedicated partition
need to expand as illustrated in figure 1.
Automated Media Pool (AMP) Partition (96-slots)
Partition 1 (24-slots) Partition 2 (24-slots)
Figure 1: A theoretical layout of
partitions within an HP ESL G3
Tape Library