HP XP P9500 Storage - Manual (Page 18)

3 Planning for Continuous Access Synchronous
This chapter provides information and instructions for planning primary and secondary systems,
pair volumes, data paths, and the other elements.
Preparing P9500 systems
The following preparations are required for the storage systems in a Continuous Access Synchronous
pair relationship:
•
Remote Web Console must be LAN-attached to the primary and secondary systems. See the
HP P9000 Remote Web Console User Guide for information.
•
The primary and secondary systems must be set up for Continuous Access Synchronous
operations. See
“Ensuring adequate cache” (page 18) . Make sure to consider the amount of
Cache Residency data that will be stored in cache when determining the amount of cache for
Continuous Access Synchronous operations.
•
Make sure that the primary system is configured to report sense information to the host. The
secondary system should also be attached to a host server to reporting of sense information
in the event of a problem with a S-VOL or secondary system. If the system is not attached to
a host, it should be attached to a primary system host server so that monitoring can be
performed.
•
If power sequence control cables are used, set the power select switch for the cluster to LOCAL
to prevent the primary system from being powered off by the host. Make sure the S-VOL is
not powered off during Continuous Access Synchronous operations.
•
Install the data path between the primary and secondary systems. Distribute data paths between
different storage clusters and extenders or switches to provide maximum flexibility and
availability. The logical paths between the primary and secondary systems must be different
than the logical paths between the host and secondary system. See
“Planning data paths”
(page 25) for more information.
Ensuring adequate cache
Cache must be operable for the pair’s primary and secondary systems, otherwise the create pair
operation fails. The secondary system cache should be configured to adequately support Continuous
Access Synchronous remote copy workloads as well as any local workload activity.
An additional shared memory is prerequisite in both of the primary and secondary systems to
create and operate the Cnt Ac-S pairs on both of the systems.
NOTE: Neither cache nor shared memory can be added to or removed from the disk array when
pair status is COPY. When either of these tasks is to be performed, first split any pairs in COPY
status; then resynchronize the pairs when the cache or shared memory operation is completed.
Installing or removing cache memory or shared memory
Cache memory or shared memory cannot be installed or removed while a Continuous Access
Synchronous pair is in COPY status. Before installing or removing cache memory or shared memory,
check the pair status. If the pair status is COPY, split the pair, install or remove cache memory or
shared memory, and then resynchronize the pair.
Using an earlier model storage system
•
If you are creating a Continuous Access Synchronous pair using an XP storage system at the
remote site, make sure that both the primary and secondary systems have a unique 5 digit
18 Planning for Continuous Access Synchronous