HP StorageWorks XP24000 Continuous Access Journal Software User and Reference Guide, v01 (T5278-96001, June 2007)

Table 6 Consistency Status for Split/Sus p ended Continuous Access Journal Secondar y
Data Volumes
Consistency Status
(Displayed at Secondary
Storage System)
Description
Volume
This Continuou
s
Access Journal data volume pair was split or suspended
alone. Update
sequence consistency between this secondary data volume
and
other seco
ndary data volumes in this journal group is not ensured.
This secondary data volume cannot be used for disaster recovery at the
secondary site. This status is indicated when:
This pair was split by the user using the Suspend Range-Volume (LU)
pairsplit option.
This pair was s uspended due to a failure tha t did not affect the entire
journal group.
Group
This Continuous Access Journal da ta volume pair was split or suspended
along
with the other pairs in its journal group. Update sequence consistency
between this secondary data volume and other secondar y data volumes in
this journal group is ensured. This secondary data volume can be used for
disaster recovery at the secondary system (after releasing the Continuous
Access Journal data volume pair from the secondary storage system). This
status is indicated when:
This pair was split by the user using the Suspend Range-Group pairsplit
option.
All pairs in this journal group were suspended due to a failure that affected
the entire journal group (not just one pair) (for example, a primary storage
system-secondary storage system communications failure).
One
pair in the group was suspended due to a failure that did not a ffect
theentiregroup.
Suspend Types
Table 7 on page 38 lists and describes the Continuous Access Journal suspend types, which indicate the
reason for the suspension. Continuous Access Journal pairs can be s uspended by either the primary
storage system or secondar y storage system. For further information on Continuous Access Journal
suspe
nsion conditions, see “Suspension Conditions”onpage38.
The pr
imary storage system suspends a Continuous Access Journal pair when it detects any of the
foll
owing suspension conditions:
• When the primar y storage system detects that the user has released the da ta volume pair from the
secondary storage system,
• When
the
primary storage system detects an error c ondition related to the secondar y storage
system, secondary data volume, or Continuous Access Journal update copy operation,
• When the primary storage system is unable to communicate with the secondary storage system,
• Whe
n
the primary storage system detects a Continuous Access Journal suspension condition.
Whe
n a
Continuous Access Journal pair is suspended, the primary storage system stops performing
jou
rnal obtain operations for the pair. The primary storage system continues accepting write I/Os
fo
r
the suspended primary data volume and keeps track of the primary data volume cylinders/tracks
which are updated while the pair is suspended. The primary storage system and secondary storage
system also keep track of any journal data that was discarded during the pair suspension. When the
suspended Continuous Access J ournal pair is resumed (pairresync) , the secondary storage system sends
t
he
secondary data volume bitmap to the primary storage system, and the primary storage system merges
t
he
primary data volume and secondary data volume bitmaps to determine which cylinders/tracks are
out-of-sync. The primary storage system merges the primary da ta volume and secondary data volume
bitmaps to identify the o ut-of-sync cylinders/tracks. This method ensures that a ll cylinders/tra cks which
contain journal data that were discarded at the secondary storage system are resynchronized at this time.
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