HP XP Cache LUN Software - Manual (Page 9)

Cache LUN XP user guide for the XP12000/XP10000/SVS200 9
1 Cache LUN Introduction
Use HP StorageWorks Cache LUN XP to reserve areas of cache memory on the disk array for storing
high-use data from the LDEVs. Data access speed is improved because the cache-resident data is available
to the hosts at much faster transfer speeds. This can be applied to both read and write I/O operations.
Supported volumes
Cache LUN XP works with normal volumes, LUSE volumes, and custom volumes (configured through CVS).
Use custom volumes and Cache LUN XP together to achieve higher data access performance (than when
these features are used separately).
Cache LUN XP tasks
Use Cache LUN XP to perform the following tasks:
• ” Setting (creating) a cache extent ” on page 18
• ” Releasing (removing) a cache extent ” on page 20
•
” Changing an extent’s mode and pre-staging ” on page 21
Figure 1 Cache LUN XP operations
Cache LUN XP requires a portion of cache memory, called the Cache LUN XP cache area. You can
change the capacity of the Cache LUN XP cache area when installing or removing cache memory.
Typically, data assigned to Cache LUN XP becomes resident ( staged) in cache after it is first accessed by a
host. Then, the host finds the data in cache for the second and subsequent accesses.
Another function, called pre-staging, puts data in the Cache LUN XP cache area when the data is first set
up for caching. Pre-staging allows the host to find data in the cache at the first access.
Cache areas (also called
cache extents) can be added or removed at any time. Each cache extent is
defined as a range of logical blocks within an LDEV or as an entire LDEV. Logical blocks are defined by
starting and ending Logical Block Addresses (LBAs).
Supported emulation types and other parameters
Supported emulation types
Supported open system emulation types are OPEN-3, OPEN-8, OPEN-9, OPEN-E, OPEN-L, and OPEN-V.
Supported mainframe emulation types are 3390-3, 3390-3A, 3390-3B, 3390-3C, 3390-3R, 3390-9,
3390-9A, 3390-9B, 3390-9C, 3390-L, 3390-LA, 3390-LB, 3390-LC, 3390-M, 3390-MA, 3390-MB, and
3390-MC.
Modified volume types
LUSE (LU Size Expansion) and CVS (custom volume size) volumes can be placed in the Cache LUN XP
cache area.
If you want to apply Cache LUN XP to a LUSE volume, you must apply Cache LUN XP to all the LDEVs that
form the LUSE volume.