Building Disaster Recovery Serviceguard Solutions Using Metrocluster with 3PAR Remote Copy for Linux B.01.00.00, July 2013

1 Introduction
This document describes the procedure to configure data replication solutions using HP 3PAR
storage systems to provide disaster recovery for Serviceguard clusters over long distances. This
chapter describes the HP 3PAR Remote Copy software and the additional files that integrate the
HP 3PAR storage system with Metrocluster.
Overview of HP 3PAR concepts
The 3PAR storage systems are configured for use in data replication from one 3PAR storage system
unit to another. This type of physical data replication is a part of this product.
Remote Copy pairs
A Remote Copy pair is a pair of storage systems on which Remote Copy operations are performed.
Within this pair, the 3PAR storage system from which the data is being replicated is the primary
storage system. The 3PAR storage system to which the data is being replicated to is the remote or
backup storage system.
Remote Copy volume groups
Remote Copy operations are performed on groups of virtual volumes called Remote Copy volume
groups. Remote Copy ensures that the replication of data in the volumes within a Remote Copy
volume group maintains write order consistency.
Remote Copy operations are started or stopped, for the whole group. When point-in-time snapshots
of such volumes are created, writes to all volumes in the group are blocked to ensure a consistent
point-in-time copy of the whole volume group. The set of volumes on the primary storage system
to be copied is known as a primary volume group, and the set of copied volumes on the remote
storage system is known as a secondary volume group.
Remote Copy and thin provisioning
A Common Provisioning Group (CPG) is a user-created storage pool available to all volumes
associated with it. There are two types of virtual volumes, which draw spaces from CPGs that can
be used with Remote Copy:
• Thinly Provisioned Virtual Volumes (TPVVs)
• Fully provisioned Virtual Volumes
For TPVVs, all data and snapshot space is allocated on demand from a CPG, and for fully
provisioned virtual volumes, only the snapshot space is allocated on demand from the CPG. All
volumes used with Remote Copy must be TPVVs or fully provisioned virtual volumes.
Remote Copy volume group modes
There are two modes used by Remote Copy volume groups: synchronous and asynchronous
periodic.
In synchronous mode, a host-initiated write is performed on both the primary and the backup
storage systems before host writes are acknowledged. In the case of a disaster that affects the
primary storage system, the copy stored on the backup storage server at the remote site, can be
immediately used to continue the application. This copy is an exact replica of the primary storage
system.
In the asynchronous periodic mode, host writes are performed only on the primary storage system
and the host write is acknowledged when the data is written into cache on the primary storage
system. The primary and backup volumes are resynchronized periodically at scheduled time or
Overview of HP 3PAR concepts 5