StorageTek SL8500, User Manual

Page: 31 / 142

Maximizing Library Performance when Partitioning
Partitioning the Library 5-5
2.
Selects a half rail
3.
Allocated half rail to red partition
4.
Available quarter rail
5.
Selected quarter rail (indicated by the thick black border)
Sharing CAPs in a Partitioned Library
In a partitioned library, hosts can share CAPs. Each host can reserve the CAP when
needed, and then release the CAP when it is no longer required. A host can reserve a
CAP if the CAP is empty, closed, locked, and not already reserved by another
partition. CAP auto enter mode is disabled in partitioned libraries, because it interferes
with the reservation system (see
"Auto Enter Mode" on page 6-5).
If the partition does not release the CAP reservation and you cannot terminate the
enter or eject command in ACSLS or ELS, a library administrator must override the
reservation (see
"Overriding a CAP Reservation of a Partition" on page 6-3).
Resolving Orphaned Cartridges Caused by Partitioning Changes
In partitioned libraries, an orphaned cartridge is in a slot not allocated to the original
host. Orphaned cartridges can occur when you change the size of a partition, delete a
partition, or move a cartridge to a slot or drive that is not allocated to a partition.
In a partitioned library, orphaned cartridges can cause data loss. A host that finds an
orphaned cartridge in its partition may treat the cartridge as a scratch volume and
overwrite the data.
SLC will warn you when it identifies orphaned cartridges. To resolve orphaned
cartridges:
■
Generate a report of orphaned cartridges (see "Generating Active Capacity
Reports" on page 12-2 )
■
Audit the library (see "Auditing the Library" on page 10-1)
■
Perform a recovery move on the cartridge (see "Moving Cartridges (Recovery
Moves)" on page 8-1)
Maximizing Library Performance when Partitioning
■
Partition storage slots in the largest blocks possible (rails, library sides, or library
walls). Partition complete library rails to minimize the use of elevators. In a library
complex, keep a partition contained within a library to minimize the use of PTPs.
■
For best access to drives, activate inner and outer library walls together.
■
Avoid partitioning individual drives and storage slot arrays. Individually select
and deselect resources only when you need to fine-tune a capacity that has already
been broadly defined in larger blocks.
■
For quicker enter and ejects, partition storage slots close to the CAPs. For quicker
access to stored data, partition storage slots close to the drives.