HP P6000 Cluster Extension Software Administrator Guide (5697-2274, November 2012)

HP P6000 Continuous Access
Figure 4 (page 11) shows the supported P6000 Cluster Extension configuration.
Figure 4 Supported P6000 Cluster Extension storage system configuration
Synchronous replication
Using synchronous mode, all write requests from the server are first transferred to the remote storage
system. After each I/O has been mirrored in the cache area of the remote array, it is acknowledged
to the local storage system. The write request is then acknowledged to the server.
Asynchronous replication
Enhanced asynchronous mode is supported by P6000 Cluster Extension 4.00.01 and later.
Using asynchronous mode, the source array acknowledges I/O completion before replicating the
data on the destination array. Asynchronous replication prioritizes response time over data currency.
Enhanced asynchronous write mode uses the write history log for the DR group as a journal to
hold I/Os waiting to be replicated to the remote array.
NOTE: For complete information on which write modes are supported on each version of controller
software, see the HP Enterprise Virtual Array Compatibility Reference.
HP P6000 Continuous Access DR groups
You must configure a single DR group for a cluster group in MSCS. This DR group must include all
vdisks being used for the application service.
The DR group is the unit in which P6000 Cluster Extension failover operations are carried out.
See the HP P6000 Continuous Access Implementation Guide for more information.
Rolling disaster protection and snapshots/snapclones
To implement rolling disaster protection, you can create P6000 Business Copy disk pairs for DR
groups locally. The P6000 Business Copy snapshots or snapclones must not be presented to the
local cluster node because MSCS uses the disk's signature to identify a cluster disk, and the cluster
software cannot differentiate between the original disk and the clone if both are presented to the
same server.
HP P6000 Continuous Access 11