A journal volume consists of two areas: one area is used for storing journal data, and the other area is used for storing metadata for remote copy.
RAID configuration:
Journal volumes support all RAID configurations that are supported by USP V. Journal volumes also support all physical volumes that are supported by USP V.
Support for program products:
The volumes on which Cache Residency Manager settings are made can be used for journal volumes.
Caution: Volumes containing a VMA (volume management area) cannot be used as journal volumes. For detailed information about a VMA, please refer to the Data Retention Utility User's Guide.
Restrictions on Journal Volumes
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:
–When the journal group does not contain data volumes (i.e., before you create a data volume pair for the first time in the journal group, or after all data volume pairs are released)
–When all data volume pairs in the journal group are suspended.
–When processing for changing the status of a data volume pair (for example, release or suspension of 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 Storage Navigator computers to register journal volumes.
If you add a journal volume when a remote copy operation is in progress (i.e., when at least one data volume pair exists for data copying), the metadata area of the journal volume (see the next section) will be unused and only the journal data area will be used. To make the metadata area usable, you need to split (suspend) all the data volume pairs in the journal group and then restore (resynchronize) the pairs.
Adding journal volumes during a remote copy operation will not decrease the metadata usage rate if the metadata usage rate is high.
Adding journal volumes during a remote copy operation may not change the journal data usage rate until the journal volumes are used. To check the journal data usage rate, use the Usage Monitor window (see Usage Monitor Window).
Chapter 3 Preparing for Universal Replicator z/OS Operations |
