Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

One-to-One Volume Copy Operations
Continuous Access Journal requires a one-to-one relationship between the logical volumes of the
volume pairs. A volume can only be assigned to one journal group pair at a time.
NOTE: Continuous Access Journal does not support operations in which one primary data volume
is copied to more than one secondary data volume, or more than one primary data volume is
copied to one secondary data volume.
One-to-One Journal Group Operations
The Continuous Access Journal supported configuration for a journal group pair is a one-to-one
relationship. This means one journal group in one P9000 or XP can only pair with one journal
group in another P9000 or XP.
Journal Group Requirement
The journal groups require that each data volume pair be assigned to one and only one journal
group.
Configuring Continuous Access Journal
One journal group can contain multiple journal volumes. Each of the journal volumes can have
different volume sizes and different RAID configurations. Journal data will be stored sequentially
and separately into each journal volume in the same journal group, and each of the journal volumes
that are used equally.
Journal volumes in the same journal group can be of different capacity. A journal volume in primary
subsystem and the corresponding restore journal volume can be of different capacity.
Registering Journal Volumes
Unlike the Continuous Access Asynchronous device group that only contains data volumes, a
journal group includes data volumes as well as journal volumes. Journal volumes must be registered
in a journal group before creating a data volume pair for the first time in the journal group.
Journal volumes are assigned to a specific journal group. Each journal group has it own ID. The
journal volumes assigned to the specific journal group can be used to create one journal group
pair.
One journal group (JID) on primary array and one journal group (JID) on secondary array are
used to create a journal group pair. Be sure to register journal volumes to journal groups on both
primary and secondary arrays. The number and capacity of the journal volumes for a specific
journal group on a primary or secondary array depends on the business need and IT infrastructure.
To register journal volumes in a journal group use the “HP StorageWorks P9000 or XP Remote
Web Console”.
Journal volumes can be registered in a journal group or can be deleted from a Journal group.
Journal volumes cannot be registered or deleted when data copying is performed (that is, when
one or more data volume pairs exist).
The journal volumes can be deleted from a journal group in the following occasions:
• When the journal group does not contain data volumes (that is, before a data volume pair is
created for the first time in the journal group, or after all data volume pairs are deleted).
• When all data volume pairs in the journal group are suspended.
If a path is defined from a host to a volume, do not register the volume as a journal volume and
define paths from hosts to journal volumes. This means that hosts cannot read from and write to
journal volumes.
162 Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP