HP XP Array Manager Software - Manual (Page 6)

2 About Cache Residency Manager Operations
This chapter describes and provides instructions for Cache Residency operations using the licensed
storage system HP Remote Console — Remote Web Console software. The Remote Web Console
software communicates directly with the storage systems via a LAN. The Remote Web Console
software displays detailed Cache Residency information and allows you to configure and perform
Cache Residency operations for the data stored on the storage system.
•
“Pre-staging Specific Data” (page 6)
•
“Cache Residency Modes” (page 7)
•
“Using Pre-staging for Immediate Data Access in Priority and Bind Modes” (page 8)
Cache Residency operations support both OPEN-V volumes and mainframe volumes (for example,
3390-3, 3390-9, z/OS, etc.). For information about open-system volumes other than OPEN-V (for
example, OPEN-3, OPEN-9, OPEN-L, etc.), see Appendix A.
Cache Residency can be used in conjunction with Virtual LVI/LUN to achieve better performance
improvements than when either of these options is used individually. If you need to store an entire
mainframe or open-system volume in Cache Residency cache, you can use a small Virtual LVI/LUN
volume to decrease the amount of cache required for the volume. For further information on Virtual
LVI/LUN, see HP StorageWorks XP24000/XP20000 Virtual LVI/LUN (VLL) and Volume Shredder
User Guide.
Cache Residency is a storage system feature that allows you to store frequently accessed data in
a specific area of the subsystem’s cache memory. Cache Residency increases the data access
speed for the cache-resident data by enabling read and write operations to be performed at high
speeds (see
“Cache Residency Cache Area” (page 6) ). When data specified as the target of
Cache Residency operation is accessed by a host system for the first time, it becomes resident or
staged in the Cache Residency cache and the host accessing the data thereafter will find it there.
You must allocate a certain portion of the subsystem’s cache memory in order to use the Cache
Residency functions. You can change the capacity of the Cache Residency cache by increasing
or decreasing the size of the cache memory allocation.
Pre-staging Specific Data
Cache Residency supports pre-staging data. This option places specific data in the Cache Residency
cache before it is accessed by the host. When pre-staging is selected, the host is able to find the
pre-staged data in the Cache Residency cache from the first access, thus enhancing its access
performance.
Figure 1 Cache Residency Cache Area
Caution: Increase total subsystem cache capacity when using Cache Residency to avoid data
access performance degradation for non-Cache-Residency data. Cache Residency is only available
6 About Cache Residency Manager Operations