HP StorageWorks XP Remote Web Console Software - Manual (Page 40)

40 Continuous Access XP Journal
CAUTION: When a pair is created, the disk array stores information about the remote disk array and
connection paths for the journal group. This information remains stored even after the pair is deleted.
Therefore, to delete a pair and then use the journal group to create a new pair with another remote disk
array, you must first delete the journal group and then create the same journal group again.
NOTE: When Continuous Access XP Journal and Universal Replicator for z/OS coexist in the same disk
array, each journal group must contain either Continuous Access XP Journal pairs or Universal Replicator
for z/OS pairs (not both).
Accessing Continuous Access XP Journal primary and secondary data volumes
To ensure maximum data integrity during normal Continuous Access XP Journal operations, the secondary
disk array rejects all write operations issued by a host to a Continuous Access XP Journal secondary data
volume. If you need a write operation to a Continuous Access XP Journal secondary data volume, you must
set the secondary data volume write option (see ” Secondary data volume write option ” on page 25).
When you resume (Pairresync) the split pair, the secondary disk array sends the secondary data volume’s
track bitmap to the primary disk array to ensure proper pair resynchronization.
Cache and nonvolatile storage (NVS)
Cache and nonvolatile storage (NVS) must be operable for the primary and secondary disk arrays of a
Continuous Access XP Journal data volume pair. If not, the Continuous Access XP Journal paircreate
operation fails. The remote disk array cache should be configured to adequately support Continuous
Access XP Journal remote copy workloads and local workload activity.
Duplicate volumes
Because the contents of the primary data volume and secondary data volume of a Continuous Access XP
Journal pair are identical, the secondary data volume can be considered a duplicate of the primary data
volume. Because 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
Continuous Access XP Journal 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.
Continuous Access XP Journal does not allow the secondary data volume to be online (except while the
pair is split). If the secondary data volume is online, the Continuous Access XP Journal paircreate
operation will fail.
CAUTION: If the Continuous Access XP Journal secondary data volume is physically attached to the same
host servers as the Continuous Access XP Journal primary data volumes, the old secondary data volume is
usually offline when a Continuous Access XP Journal pair is deleted. If the host is then restarted, the system
administrator might be offered both volumes and asked which volume should be left offline. This can be
confusing and is prone to error.
If the Continuous Access XP Journal secondary data volumes and primary data volumes are connected to
the same hosts, HP strongly recommends that secondary data volumes are defined to remain offline to
avoid this problem.
Port configurations
When configuring a system for using Continuous Access XP Journal, ensure that ports are configured
correctly.
Table 16 and Table 17 explain cases of illegal port configurations. For example, as the first row of
Table 16 indicates, if you use the CL1-A port as an RCU target port in the Continuous Access XP Journal
primary site, you must not use the CL1-A or CL5-A port as a target port in the Continuous Access XP Journal