HP XP P9500 Storage - Manual (Page 44)

The following operations automatically reset Cache Residency cache:
◦ When LDEVs that is partly or wholly assigned to Cache Residency is deleted.
◦ When the parity group containing LDEVs that are assigned to Cache Residency is deleted.
Figure 6 Example of LBA Value Setting When Using LUSE
Restrictions
•
The Cache Residency bind mode is not available to external volumes whose Cache mode is
set to Disable (which is the mode that disables the use of the cache when there is an I/O
request from the host).
•
You cannot allocate pool-VOLs and V-VOLs for Cache Residency. For further information about
pool-VOLs and V-VOLs, see the HP P9000 Snapshot User Guide, the HP P9000 Provisioning
for Open Systems User Guide, or the HP P9000 Provisioning for Mainframe Systems User
Guide.
•
You cannot allocate the journal volumes for Cache Residency. For additional information
about the journal volumes, see the HP P9000 Continuous Access Journal User Guide or the
HP P9000 Continuous Access Journal for Mainframe Systems User Guide.
•
You cannot allocate the remote command device for Cache Residency. For further information
about the remote command device, see the HP P9000 External Storage for Open and
Mainframe Systems User Guide.
•
You cannot allocate a quorum disk for Cache Residency.
Guidelines
•
Performing Cache Residency operations on many LDEVs during host I/O may cause the host
I/O response time to become slow. To avoid degradation of response time, set only one LDEV
at a time.
•
Deleting data from cache during host I/O may cause the response time of host I/O to become
slow. To avoid degradation of host response time, limit the amount of data you delete in one
operation as follows:
If the host timeout period is set to 10 seconds or shorter, limit the total amount of data to:
◦ 1 GB or less for open systems
◦ 1,000 cylinders or less for mainframe systems
If the host timeout period is set to 11 seconds or longer, limit the total amount of data to:
◦ 3 GB or less for open systems
◦ 3,000 cylinders or less for mainframe systems
44 Managing resident cache