HP XP Array Manager Software - Manual (Page 13)

Overview of Hitachi Cache Manager 1-3
Hitachi Cache Manager User’s Guide
• The maximum number of extents is limited:
Universal Storage Platform V
– No more than 4096 extents per logical volume
– No more than 16384 extents for the storage system
Universal Storage Platform/Network Storage Controller
– No more than 4096 extents per logical volume
– No more than 4096 extents for the storage system
Lightning 9900V and Lightning 9900
– No more than 1024 extents per logical volume
– No more than 1024 extents for the storage system
• If a user needs an entire mainframe volume in Cache Manager, using a
smaller Virtual LVI volume will use less cache. For more information on
Virtual LVI, please refer to the Virtual LVI/LUN user document for the
storage system(s) (e.g., Hitachi TagmaStore USP and NSC LUN Expansion
and Virtual LVI/LUN User’s Guide, MK-94RD205).
• All write I/Os to cache are duplex writes, guaranteeing full data integrity.
The data remains fixed in cache until the user manually deletes it. Deletion
of extents will de-stage any write data to the affected volume(s).
• It is possible to expand the amount of cache without canceling the existing
settings. Please call the Hitachi Data Systems Technical Support Center for
assistance.
• Defragmentation will reallocate the datasets. If you want to defragment a
disk, first release the datasets and then reassign them to cache when you
are finished.
• If a BIND command to assign discontinuous plural extents to cache as one
dataset terminates abnormally, Cache Manager will automatically release
the resident area. If an error occurs in the process of releasing the resident
area, Cache Manager will display the remaining extents that should be
released. If this occurs, manually release the remaining extents then re-
execute the BIND command.
• If a BIND command to release data from cache terminates abnormally,
correct the errors and re-execute the command for the remaining area(s).
• You can reset areas that were set with Cache Manager by using Cache
Residency, and vice versa. The commands are accepted in the order in
which they were received.
• Warning: Do not attempt to simultaneously access the Cache Residency
or Cache Manager functions from more than one source, or the commands
may interfere with each other.