User's Guide

Metrocluster with Continuous Access for P9000 and XP needs to be installed on all nodes that will
run a Serviceguard package whose data are on an HP StorageWorks P9000 Disk Array family
or HP StorageWorks XP Disk Array series, and where the data is replicated to a second P9000
or XP using the Continuous Access P9000 or XP facility. In the event of node failure, the integration
of Metrocluster with Continuous Access for P9000 and XP with the package will allow the
application to fail over in the following ways:
• among local host systems attached to the same P9000 or XP Series array
• between one system that is attached locally to its P9000 or XP series array and another
“remote” host that is attached locally to the other P9000 or XP series array.
Configuration of Metrocluster with Continuous Access for P9000 and XP must be done on all the
cluster nodes, as is done for any other Serviceguard package. To use Metrocluster with Continuous
Access for P9000 or XP, P9000 or XP Raid Manager host-based software for control and status
of the P9000 or XP Series arrays must also be installed and configured on each HP 9000 or
Integrity host system that might execute the application package.
Overview of Continuous Access P9000 and XP Concepts
The HP StorageWorks P9000 Disk Array family or HP StorageWorks XP Disk Array series may be
configured for use in data replication from one P9000 and XP series unit to another. This type of
physical data replication is a part of the Metrocluster with Continuous Access for P9000 or XP and
Continentalclusters solutions. This section describes the hardware and software concepts necessary
for understanding how to use Continuous Access software for physical data replication in disaster
tolerant solutions.
PVOLs and SVOLs
Continuous Access allows you to define primary and secondary volumes that are redundant copies
of one another, as shown in Figure 27.
Figure 27 XP Series Primary and Secondary Volume Definitions
BCs are optional Business Continuity volumes that can be used for point in time local backup of
PVOL and SVOL volumes. Data replication proceeds from PVOL to SVOL. When failover is
necessary, the SVOL can be changed into a PVOL for access by a package on the failover node.
Device Groups and Fence Levels
A device group is the set of XP devices that are used by a given package. The device group is the
basis on which PVOLs and SVOLs are created. The fence level of the device group is set when you
154 Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP