HP StorageWorks XP Remote Web Console Software - Manual (Page 23)

Continuous Access XP Journal user guide 23
• 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 from a host to a volume is defined, you cannot register the volume as a journal
volume.
You can use Command View XP management stations or XP Remote Web Console to register journal
volumes.
If you add a journal volume when a remote copy operation is in progress (that is, when at least one
data volume pair exists for data copying), the journal volume’s metadata area (see ” Journal volume
areas ” on page 23) is unused, and only the journal data area is used. To make the metadata area
usable, split (suspend) all data volume pairs in the journal group, and restore (resynchronize) the
pairs.
Adding journal volumes during a remote copy operation does not decrease the metadata usage rate if
the metadata usage rate is high.
Adding journal volumes during a remote copy operation might not change the journal data usage rate
until the journal volumes are used. To check the journal data usage rate, use the Usage Monitor pane
(see ” Monitoring remote copy operations ” on page 135).
• Deleting journal volumes
You can delete journal volumes under any of the following conditions:
• The journal group does not contain data volumes (that is, before creating a data volume pair in the
journal group for the first time, or after deleting all data volume pairs)
• All data volume pairs in the journal group are suspended
You can use Command View XP management stations or XP Remote Web Console to delete journal
volumes.
• Access from hosts to journal volumes
If a path from a host to a volume is defined, you cannot register the volume as a journal volume.
You cannot define paths from hosts to journal volumes. This means that hosts cannot read from and
write to journal volumes.
Journal volume areas
A journal volume consists of a metadata area and a journal data area. The ratio of the metadata area to
the journal data area is the same on all journal volumes within the journal group.
Metadata that manages the journal data is stored in the metadata area. For more information about the
metadata area, see Table 3 on page 28. Journal data that the metadata manages is stored in the journal
data area.
NOTE: If the metadata or journal data cannot be stored for a given length of time because the metadata
or journal data areas are full with metadata or journal data that has not been discarded, the pair is
suspended. Use a Command View XP management station or XP Remote Web Console to specify this
timeout period (Data overflow watch) as a journal group option. This timeout period must be within the
range of 0 to 600 seconds. For more information, see ” Changing options for journal groups ” on
page 107.
Consistency groups
Continuous Access XP Journal consistency group numbers are equivalent to Continuous Access XP
Asynchronous consistency group numbers. Therefore, you can create a Continuous Access XP Journal pair
with consistency group numbers from RAID Manager XP as is the case with Continuous Access XP
Asynchronous. In Continuous Access XP Journal operations, consistency group numbers specified from
RAID Manager XP are assigned to the journal group numbers.