1.
Active frames are all frames in a dual-accessor library, except for service bays.
2.
The following library setup was used to obtain the stated performance data:
•
ALMS and virtual I/O slots are enabled
•
Cartridge assignment policy is setup for each logical library
•
No HD frames
3.
The data assumes that the library is partitioned into two separate zones, such that
the cartridges assigned to the logical libraries in the two zones are imported and
exported using the I/O stations within each zone with no accessor path overlap.
lists the specifications for import performance only. Export performance is designed
to be within 20% of import performance when cartridges are being exported from tier 0 and
tier 1 slots. In other words, for recently used cartridges and all cartridges in non-HD frames,
exports per hour range between 80% and 100% of imports per hour.
Import and export performance is impacted in a library with HD frames. For more
information, refer to
HD frame performance considerations
Parent topic:
HD frame performance considerations
This topic explains how mount performance, cartridge move time, and insert and eject
performance are affected in HD libraries.
In HD frames, the cartridge accessor performs a
shuffle
operation in order to access the
cartridges stored in Tier 2 and beyond. A shuffle is the process of moving cartridges in lower
tiers into the gripper, or other available slots, in order to access cartridges in higher tiers
(Tier 2 or greater). In order to reduce the occurrence of shuffle operations, and to take
advantage of repeated accesses of certain cartridges, the role of
cartridge cache
is assigned
to all single-deep (Tier 0) slots in an HD library. In order to maintain efficient shuffle
operations, the library performs a
load balancing
of the tiers, which stores cartridges across
all HD slots in the library string. In other words, all HD slots are filled to a minimum tier
level until that tier is full across the library. This reduces the need to access cartridges in
higher tiers.
The mount performance for a TS3500 Tape Library that includes HD frames is dependent on
the library configuration and cartridge usage. For most configurations, the impact is not
noticeable. For configurations with high accessor utilization (as measured in mounts per
