IBM System Storage TS3500, Manual

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Mount performance and cartridge move time
This section describes mount performance and cartridge move times for the TS3500 Tape
Library.
Mounts per hour is a measure of the overall capability of the cartridge accessor and tape
drives. It is defined as the number of cartridges that the TS3500 Tape Library can mount in
one hour. A mount, often called the demount and mount cycle, involves the following steps:
(1) removing the cartridge from a drive; (2) returning it to a storage slot; (3) collecting
another cartridge from a random storage slot; (4) moving it to the drive; and (5) loading
the cartridge into the drive.
Move time is the time required for the cartridge accessor to pick a cartridge from a random
slot, move the cartridge to a drive, pivot (if required), and insert the cartridge into the
drive.
Table 1 shows the mount performance and average move time for a TS3500 Tape Library
without dual accessors and without HD frames.
Table 1. Mount performance and move time for drives in a TS3500 Tape Library without
dual accessors and without HD frames
Library
Configuration
Drives in Frame 1 Drives in Center Frame
Mounts Per
Hour
Average Move
Time in Seconds
Mounts Per
Hour
Average Move
Time in Seconds
1 frame 550 2.7 N/A N/A
2 frames 520 2.6 N/A N/A
4 frames 410 3.3 430 2.9
6 frames 350 3.8 380 3.3
8 frames 310 4.4 350 3.7
12 frames 255 5.3 300 4.3
16 frames 215 6.2 260 4.7
Specifications were produced from models, but are consistent with test results.
Table 2 shows the mount performance for a TS3500 Tape Library with dual accessors but
without HD frames.
Table 2. Mount performance for drives in a TS3500 Tape Library with dual accessors but
without HD frames
Library Configuration
(Active Frames 1 )
Mounts Per Hour 2
4 frames 1000
6 frames 900