HP 3PAR Remote Copy Software - Manual (Page 22)

2.6 Remote Copy Volume Groups
Remote Copy User’s Guide InForm OS Version 2.3.1
2.3 Remote Copy Volume Groups
Remote Copy operations are performed on groups of virtual volumes called Remote Copy
volume groups. A Remote Copy volume group is a group of volumes on the same storage
system that are logically related and for which there is a cross-volume ordering of writes.
Volume groups are used when data needs to be consistent across a group of volumes in order
for database or other applications to process data correctly.
Remote Copy uses volume groups to define a set of volumes for which applications might issue
dependent writes.
Remote Copy ensures that the data in the volumes within a group maintain write consistency.
When Remote Copy operations are started or stopped, this is done for the whole group. When
point-in-time snapshots of such volumes are created, writes to all volumes in the group are
blocked to assure a consistent point-in-time copy of the whole volume group.
2.4 Remote Copy Pairs
Remote Copy configurations are based on the relationship between a storage server pair, also
known as the Remote Copy pair. Within this pair, the primary storage server is the server that
holds the volumes that are copied to a backup server, also known as a remote storage server.
As described in N-to-1 Restrictions on page 2.43, a maximum of four primary storage servers
can use the same backup storage server. In such configurations, the backup storage server
participates in multiple pairs, one for each primary storage server. See Figure 2-4 for an
example of a configuration that uses multiple Remote Copy pairs.
NOTE: For any configuration, the backup storage server might be at the same
location as the primary storage server or servers, or it might reside at a remote
location. Disaster recovery applications often require that the backup storage
server reside at a remote location relative to the primary storage servers.