HP XP Continuous Access Software - Manual (Page 38)

volume is copied to the secondary data volume, or the delta resync operation finishes without any further
processing. In other words, any contingency to avoid a full DC2-to-DC3 copy in the event of a DC1
problem will be abandoned if the difference between the DC2 and DC3 data get too large to store
all the necessary delta data.
Usually, if the pair between the Continuous Access XP Synchronous primary and secondary sites is
synchronized periodically, the total capacity of journal data that is not restored to the Continuous Access
XP Journal secondary site does not exceed 80% of the journal volume. Although, for example, if the
Continuous Access XP Journal pair is suspended and the pair has not been resynchronized for a long
time, journal data of more than 80% of the journal volume capacity might exist before it is restored to
the Continuous Access XP Journal secondary data volume. In such cases, you cannot perform the delta
resync operation.
CAUTION:
Even if the journal data's capacity does not exceed 80% of the journal volume, journal data is or might
be destroyed in the following cases:
• When restoring the Continuous Access XP Synchronous pair, then updating the P-VOL
• When restoring the Continuous Access XP Journal pair between the primary site and the Continuous
Access XP Journal secondary site, then updating the P-VOL
• When retry processing occurs because of a delay in a P-VOL update
• When update processing for the Continuous Access XP Synchronous S-VOL is delayed
As shown in Figure 8 , after the delta resync operation is performed completely and primary site A (DC1)
is recovered from its failure, the Continuous Access XP Journal pair between primary site A (DC1) and
the original Continuous Access XP Journal secondary site (DC3) is then a candidate for a contingency
delta resync pairing to prepare for the eventuality of a failure at primary site B (DC2). For more
information about requirements regarding a delta resync operation, see Requirements for performing
delta resync operations .
Continuous Access XP Journal data volume pair status
Continuous Access XP Journal displays the pair status for each data volume of a specified CU Image
(CUI) in the connected local array. Table 4 describes the Continuous Access XP Journal data volume pair
statuses. The primary array maintains the primary data volume's status and can change the pair status of
the primary and secondary data volumes. The secondary array maintains the secondary data volume's
status and can change the pair status of the secondary data volumes, but not the primary data volume.
The primary array detects when the secondary array changes the secondary data volume's status (if
the path status is normal) and changes the primary data volume's status accordingly. You can display
detailed pair status information using Command View AE or XP Remote Web Console (Continuous Access
XP Journal Pairdisplay pane) or a UNIX/PC host (RAID Manager XP Pairdisplay command).
A volume that is not assigned to a Continuous Access XP Journal data volume pair has the status SMPL.
When a Continuous Access XP Journal data volume pair is started, the primary array changes the status
of the primary and secondary data volumes to COPY. When the initial copy operation is complete, the
primary array changes the status of both data volumes to PAIR. When a pair is suspended due to an
error condition, the primary array changes the status of the primary and secondary data volumes to
PSUE (if the path status is normal). When splitting a Continuous Access XP Journal pair (pairsplit-r), the
primary or secondary array changes the status of the primary and secondary data volumes to PSUS (if
the path status is normal). When a pair is split from the secondary array, the secondary array changes
the secondary data volume's status to PSUS, and the primary array detects the pair suspension (if path
status is normal) and changes the primary data volume's status to PSUS. When a pair is deleted from
the primary array, the primary array changes the status of both data volumes to SMPL. When a pair
is deleted from the secondary array, the secondary array changes the secondary data volume's status
to SMPL, and the primary array detects the pair deletion (if path status is normal) and changes the
primary data volume's status to PSUS.
When a Continuous Access XP Journal data volume pair is split or suspended, the primary array
generates a service information message (SIM) to notify the hosts. If SNMP is installed and operational
38 Overview of Continuous Access XP Journal