IBM TS4500, Введение и руководство по планированию

Страница: 26 / 218

cartridges in lower tiers into the gripper (or other available slots) to access
cartridges in higher tiers (Tier 2 or greater). To reduce shuffle operations and 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. To maintain efficient
shuffle operations, the library uses load balancing to store 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. For more information about HD frames
and library performance, see “High-Density Capacity on Demand” on page 50.
Second-generation HD (HD2) frames provide the following enhancements:
v
Can be installed in the leftmost library position (frame position 1).
v
Offer drive-capable models that support up to 16 HD2-compatible tape drives
when in frame position 2 or higher.
Note:
v
You cannot upgrade a Non-HD2 frame to an HD2 frame.
Non-HD2 frames cannot be upgraded to HD2 frames.
Top rack
The top rack, 3584 Model TR1, provides an extra 10U of rack space on any frame
in a library without requiring more floor space.
The optional top rack (Figure 4 on page 9) reduces the storage footprint. It also
simplifies cabling by providing extra rack space above the library for power
distribution units, Fibre Channel switches, tape data movers, or IBM Linear Tape
File System
™
(LTFS) nodes.
8
IBM TS4500: Introduction and Planning Guide