Terminology; Planning Library Capacity - Sun Microsystems StorageTek SL500 User Manual

Capacity on Demand Features and Restrictions
Storage capacity is incremental. Total licensed capacity is equal to the sum of the
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capacities specified in each license key file installed and activated on the library.
The order that capacity licenses are installed is not significant (that is, it does not
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need to match the order of the modules in the SL500 frame).

Terminology

The following terms are used to describe library capacity management:
Physical or installed capacity—The number of storage cells physically present in the
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library.
Licensed capacity—The number of storage cells the library is licensed to use. This
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cannot exceed the installed capacity.

Planning Library Capacity

The SL500 does not support gaps in licensed capacity; all storage cells must be
contiguous. This has the following effects on capacity planning.
You can begin adding licensed capacity to a module only if the module directly above
it is licensed at full capacity.
Example:
Deleting a Capacity license for a module in the middle of a library will cause the
modules below it to be unavailable.
Example:
Note – CEMs must be at the bottom of any SL500 configuration. A CEM cannot be
installed between a Base Module and a DEM.
138 SL500 User's Guide • July 2008
Base Module + DEM
The Base Module must be licensed at full capacity before you can begin
adding licensed capacity to the DEM.
Base Module + DEM + CEM + CEM
Removing any portion of the DEM capacity will make both CEMs
unavailable.
Revision: KA • 96116