Journal groups, Data volume pairs, Journal volumes – HP StorageWorks XP Remote Web Console Software User Manual
Page 21
Continuous Access XP Journal user guide
21
XP Journal secondary data volumes). The secondary array issues read journal commands to the
primary array in order to copy journals. For Command View XP, the secondary management station
should be connected to the secondary arrays at the secondary site on a separate LAN. The secondary
arrays should also be attached to a host system to:
• Report sense information if a problem with a secondary data volume or secondary array occurs.
• Provide disaster recovery capabilities.
The local array can function simultaneously as a primary array for one or more primary data volumes and
as a secondary array for one or more secondary data volumes if the remote copy connections and Fibre
Channel interface ports are properly configured. You can use Continuous Access XP Journal to specify the
secondary array from the connected primary array. You can perform Continuous Access XP Journal
operations on all LDEVS except Command View XP or XP Remote Web Console command devices. For
more information about local array command devices, see the HP StorageWorks LUN Configuration and
Security Manager XP user guide for the XP12000/XP10000/SVS200.
NOTE:
When configuring a journal group pair, you must specify the serial numbers of the primary and
secondary arrays. You must specify different serial numbers for the primary array and secondary array for
a journal group pair. If you must specify the same serial number, contact your HP account support
representative.
Journal groups
A journal group consists of two or more data volumes and journal volumes. You can use a journal group
to tailor Continuous Access XP Journal for your unique business content. The journal volume in the primary
array is referred to as the master journal volume. The journal volume in the secondary array is referred to
as the restore journal volume. The data volume in the master journal group is also called the primary data
volume. The journal volume in the master journal group is called the master journal volume. The data
volume in the restore journal group is similarly called the secondary data volume. The journal volume in
the restore journal group is called the restore journal volume.
The data update sequence from the host is managed at the level of the journal group. The data update
sequence consistency between the master and restore journal groups is maintained and ensured. The
master and restore journal groups are managed based on a journal group number. The journal numbers
of paired master and restore journal groups can be different. One data volume and one journal volume
can belong to only one journal group.
Data volume pairs
Continuous Access XP Journal performs remote copy operations for data volume pairs that you create.
Each Continuous Access XP Journal pair consists of one primary data volume and one secondary data
volume, which are typically located in different arrays. Continuous Access XP Journal primary data
volumes are the primary volumes (LUs) containing the original data. Continuous Access XP Journal
secondary volumes are the secondary volumes (LUs) containing the backup or duplicate data. During
normal Continuous Access XP Journal operations, the primary data volume remains available to hosts at
all times for read and write I/O operations. During normal Continuous Access XP Journal operations, the
secondary array rejects all host-requested write I/Os for the secondary data volume. The secondary data
volume write enable option allows write access to a secondary data volume while the pair is split and can
use secondary and primary data volume track maps to later resynchronize the pair (see ”
Continuous Access XP Journal also supports Volume Manager and Cache LUN XP, which allows
Continuous Access XP Journal to meet a variety of user needs by way of data copying and data
migration. This ensures that all user data can be backed up or duplicated. See ”
page 40 for more information about LU requirements and support.
Journal volumes
When using Continuous Access XP Journal, updates to primary data volumes are stored in other volumes,
which are called journal volumes. Updates (which are sometimes referred to as update data) that are
stored in journal volumes are called journal data.