HP StorageWorks XP Remote Web Console Software - Manual (Page 46)

journal group with two or more restore journal groups. Each pair relationship in a journal group
is called "Mirror." Mirror ID identifies two or more mirrors that one journal group has. The same
Mirror ID of the journal group is applied to the data volume pair. See
“Combining URz with TCz
Synchronous (3DC Cascading Configuration)” (page 74) .
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Table 17 (page 46) shows the specifications of relationship between the data volumes, between
the journal volumes, and between the data volumes and journal volumes in a journal group.
Table 17 Journal Group Volume Specifications
Support specifications Item
Same emulation type. Emulation type
Does not matter whether the capacity is the same or different. Volume
capacity
Journal volumes and data volumes in the same journal group can belong to different
CLPRs. Journal volumes must belong to the same CLPR. Data volumes must also belong to
the same CLPR.
A primary journal group and the corresponding restore journal group need not belong
to the same CLPR.
CLPR
NOTE: When URz and UR coexist in the same storage system, each journal group must contain
either URz pairs or UR pairs (not both).
Accessing URz Primary Data Volume and Secondary Data Volume
To ensure maximum data integrity during normal URz operations, the secondary storage system
rejects all the read/write operations issued by a host to a URz secondary data volume. If you need
write operation to a URz secondary data volume, you must set the secondary data volume write
option (see
Secondary Data Volume Write Option ). When you resume (Resume Pair) the split pair,
the secondary storage system will send the secondary data volume track bitmap to the primary
storage system to ensure proper resynchronization of the pair.
Cache and Nonvolatile Storage (NVS)
Cache and nonvolatile storage (NVS) must be operable for both the primary storage system and
secondary storage system of a URz data volume pair. If not, the URz add pair operation will fail.
The remote storage system cache should be configured to adequately support not only the local
workloads but also the URz remote copy workloads.
Duplicate Volumes
Since the contents of the primary data volume and secondary data volume of a URz pair are
identical, the secondary data volume can be considered a duplicate of the primary data volume.
Since the host operating system does not allow duplicate volumes, the host system administrator
must take precautions to prevent system problems related to duplicate volumes. You must define
the URz secondary data volume so they do not auto-mount or come online to the same host at the
same time as the primary data volume (see WARNING below).
46 Requirements and Restrictions for Universal Replicator z/OS Operations