Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access XP P9000 for Linux B.01.00.00

1 Introduction
This document describes the Continuous Access P9000 and XP software and the additional files
that integrate the XP or P9000 Disk Arrays with Metrocluster. The document explains how to
configure Metrocluster using Continuous Access XP or P9000.
Overview of Continuous Access P9000 and XP concepts
Continuous Access is the physical data replication technology that can be used to replicate data
from a XP or P9000 series disk arrays to a different XP or P9000 series disk array, at a far away
location. The Metrocluster with Continuous Access for XP 9000 integrates Serviceguard failover
mechanism with Continuous Access replication and automates application failover across data
centers while appropriately manipulating the replication for different type of disasters. This section
describes the hardware and software concepts necessary for understanding how to use Continuous
Access software for physical data replication in disaster recovery solutions.
PVOLs and SVOLs
Continuous Access allows you to define primary volumes (PVOLs) and secondary volumes(SVOLs)
that are redundant copies of one another, as shown in Figure 1 (page 6). The relationship between
a PVOL and an SVOL is called a pair.
Figure 1 PVOLs and SVOLs
Optional
BCs
DataCenter A
Device Group
Redundant, Continous Access Links with DWDM
Disk Array
BC1
BC2
PVOL
PVOL
SVOL
DataCenter B
Disk Array
Optional
BCs
SVOL
SVOL
PVOL
BC3
BC4
BCs are the optional Business Copies 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
A device group is a set of PVOL-SVOL replication pairs between two P9000 or XP disk arrays
Figure 1 (page 6). In Metrocluster all the replicated LUNs used by an application are configured
in a single Device Group.
6 Introduction