Elastic capacity

In a dual-accessor configuration, the TS4500 tape library contains limited access columns that you can use for special situations. You can use these columns to store least recently used data cartridges, or as a temporary overflow area. The use of the limited access columns (Elastic Capacity) allows dual-accessor customers to achieve the same storage capacity as if the library was single accessor.

Elastic Capacity Settings

Go to Settings > Library > Advanced in the TS4500 tape library GUI to modify the Elastic Capacity settings. Choose one of the three options for Elastic Capacity.

Use for maximum capacity

Use this setting to store media cartridges in the limited access (Elastic Capacity) columns. When the dual-access area (the cartridge slots that both A and B accessors can reach) exceeds the usage threshold, the least recently used cartridges are move into the Elastic Capacity area. The default usage threshold is 98%.

Use for temporary overflow

Use this setting to temporarily store media cartridges in the limited access (Elastic Capacity) columns. When the dual-access area is 100% full, new cartridges that are imported from the I/O stations are moved to the Elastic Capacity areas.

Do not use

Choose this setting if you do not want any media cartridges stored in the Elastic Capacity areas.

Limited Access

The Elastic Capacity slots are limited access when an accessor is placed in service. When the A accessor is in the Integrated Service Bay A (see  1  in Figure 1), the B accessor cannot reach columns 3-8 in that frame. The only cartridges the B accessor can access are in column 9 (see  3  in Figure 1) and column 10 on the door-side.

Figure 1. A-accessor in Service Bay A

When the B accessor is in the Integrated Service Bay B (See  2  in Figure 2), the A accessor cannot reach columns 5-10 in that frame. The only cartridges the A accessor can reach are in columns 1, 3  1  and door-side columns 2 and 4.

Figure 2. B-accessor in Service Bay B

Cartridge Movement

The movement of cartridges into the Elastic Capacity area is automated by the library firmware. The movement of cartridges from the Elastic Capacity area is not automated by the library firmware - that movement occurs when requested by the application, GUI, or CLI.