HP StorageWorks XP Remote Web Console Software - Manual (Page 19)

Continuous Access XP Journal user guide 19
communications path between the primary disk array and secondary disk array fails temporarily, remote
copy operations continue after the communications path is recovered.
If data transfer from hosts to the primary disk array is temporarily faster than data transfer between the
primary disk array and secondary disk array, remote copy operations between the primary disk array and
secondary disk array continue. Because journal volumes can contain more update data than cache
memory can contain, remote copy operations continue if data transfer from hosts to the primary disk array
is faster than data transfer between the primary and the secondary disk array for a relatively long period
of time.
Number of journal volumes
One journal group can contain up to 16 journal volumes. Each journal volume can have different volume
sizes and RAID configurations. Journal data is stored sequentially and separately into each journal volume
in the same journal group.
Journal volume specifications
• Logical units (LUs) types
The only DKU emulation type allowed for journal volumes is OPEN-V.
• Volumes and capacities
You can use custom volumes for journal volumes.
Journal volumes in the same journal group can have different capacities. A master journal volume and
the corresponding restore journal volume can have different capacities.
A journal volume consists of two areas: one area is used to store journal data and the other area is
used to store metadata for remote copy.
• RAID configurations
Journal volumes support all RAID configurations that the local disk array supports. Journal volumes also
support all physical volumes that the XP10000/XP12000 supports.
Volumes in parity groups of RAID-5 (7D+1P) configuration are usually used as journal volumes.
• Support for option programs
You can use HP Cache LUN XP volumes for journal volumes.
CAUTION: Volumes containing a VMA (volume management area) cannot be used as journal
volumes. For more information about VMA, see the HP StorageWorks LUN Security XP Extension
User Guide.
Journal volume restrictions
• Registering journal volumes
CAUTION: You must register journal volumes in a journal group before you create a data volume
pair for the first time in the journal group.
You can add journal volumes under any of the following conditions:
• The journal group does not contain data volumes (that is, before creating a data volume pair for the
first time in the journal group or after deleting all data volume pairs)
• All data volume pairs in the journal group are suspended
• Processing for changing a data volume pair’s status (for example, deleting or suspending a data
volume pair) is not in progress
NOTE: If a path is defined from a host to a volume, you cannot register the volume as a journal
volume.
You can use Command View XP computers or XP Remote Web Console to register journal volumes.