HP StorageWorks XP Remote Web Console Software - Manual (Page 28)

Journal Group Operations
Universal Replicator for Mainframe provides the following group-based operations to simplify and
expedite disaster or failure recovery procedures:
•
Group operations at the primary storage system
Split all pairs in a journal group. For a description of the Group option, see “Splitting a
Mirror (Suspending a Copy Operation)” (page 172) .
◦
◦ Resume all suspended pairs in a journal group. For a description of the Universal Replicator
for Mainframe Resume Range-Group resume pair option, see
“Restoring a Mirror (Resuming
a Copy Operation)” (page 174) .
◦ Release all pairs in a journal group. For a description of the Delete Range-Group delete
pair option, see
“Deleting Data Volumes from a Mirror (Ending a Copy Operation)”
(page 174) .
•
Group operations at the secondary storage system
Split (suspend pair) all pairs in a journal group. For a description of the Group option,
see
“Splitting a Mirror (Suspending a Copy Operation)” (page 172) .
◦
◦ Release (delete pair) all pairs in a journal group regardless of their consistency status.
For a description of the Delete Range-Group delete pair option, see
“Deleting Data
Volumes from a Mirror (Ending a Copy Operation)” (page 174) .
Read and Write I/O Operations During Universal Replicator for Mainframe
Operations
When a primary storage system receives a read I/O for a Universal Replicator for Mainframe
primary data volume, the primary storage system performs the read from the primary data volume.
If the read fails, the redundancy provided by RAID-1 or RAID-5 technology recovers the failure.
The primary storage system does not read the Universal Replicator for Mainframe secondary data
volume for recovery.
When a primary storage system receives a write I/O for the primary data volume with PAIR status,
the primary storage system performs the update copy operation, as well as writing to the primary
data volume.
The primary storage system completes the primary data volume write operations independently of
the update copy operations at the secondary data volume. The secondary storage system updates
the data in the secondary data volume according to the write sequence number of the journal data.
This will maintain the data consistency between the primary and secondary data volumes. If the
primary data volume write operation fails, the primary storage system reports a unit check and
does not create the journal data for this operation. If the update copy operation fails, the secondary
storage system suspends either the affected pair or all Universal Replicator for Mainframe pairs in
the journal group, depending on the type of failure. When the suspended Universal Replicator for
Mainframe pair or journal group is resumed (Resume Pair), the primary storage system and
secondary storage system negotiate the resynchronization of the pair(s). See
“Suspend Types”
(page 40) for further information on Universal Replicator for Mainframe suspend types.
During normal Universal Replicator for Mainframe operations, the secondary storage system does
not allow Universal Replicator for Mainframe secondary data volumes to be online (mounted), and
therefore hosts cannot read from and write to secondary data volumes. The Universal Replicator
for Mainframe secondary data volume write enable option allows write access to a secondary
data volume while the pair is split (see the next section). The secondary data volume write option
can only be enabled when you split the pair from the primary storage system.
28 About Universal Replicator for Mainframe Operations