HP XP Continuous Access Software - Manual (Page 41)

When the suspended XP Continuous Access Journal pair is resumed (pairresync), the primary and
secondary storage systems perform the following operations:
•
The secondary storage system sends the secondary data volume bitmap to the primary storage
system.
•
The primary storage system merges the primary data volume and secondary data volume
bitmaps to determine which cylinders/tracks are out-of-sync.
•
The primary storage system merges the primary data volume and secondary data volume
bitmaps to identify the out-of-sync cylinders/tracks.
This method ensures that all cylinders/tracks that contain journal data that was discarded at the
secondary storage system are resynchronized at this time.
Table 8 Suspend Types (PSUE)
Description Applies to Type
The primary storage system detected an error during a secondary
storage system communication or an error during an update copy.
In this case, the secondary data volume suspend type is usually
PSUE-S-VOL Failure. Primary data volume,
Secondary data volume PSUE, S-VOL
Failure
The primary storage system could not find valid control information
in its nonvolatile memory during an IMPL. This condition occurs only
if the primary storage system is without power for more than 48
hours (that is, a power failure and fully discharged backup batteries). Primary data volume,
Secondary data volume PSUE, MCU
IMPL
The XP Continuous Access Journal pair was suspended before the
initial copy operation was complete. The data on the secondary data
volume is not identical to the data on the primary data volume. Primary data volume,
Secondary data volume PSUE, Initial
Copy Failed
The primary storage system is powered off. Secondary data volume PSUE, MCU
P/S OFF
Suspension Condition
XP Continuous Access Journal operations involve additional suspension conditions related to the
asynchronous journal operations. Both the primary storage system and secondary storage system
can detect XP Continuous Access Journal suspension conditions and suspend XP Continuous Access
Journal pairs.
•
The primary storage system stores the differential bitmap for each XP Continuous Access Journal
primary data volume in the shared memory.
•
The secondary storage system stores the differential bitmap for each XP Continuous Access
Journal secondary data volume in the shared memory.
When an XP Continuous Access Journal pair is suspended, the tracks that contain the following
journals are marked in the differential bitmap as modified (to be copied during the pairresync
operation):
•
The journal data that was created by the primary storage system, but not yet sent to the
secondary storage system.
After marking these primary data volume tracks as modified, the primary storage system
discards this journal data.
•
The journal data that was sent to the secondary storage system, but not acknowledged by the
secondary storage system.
After marking these primary data volume tracks as modified, the primary storage system
discards this journal data. This ensures that journal data lost during transmission to the
secondary storage system is identified and marked.
Pair Status 41