HP StorageWorks XP Remote Web Console Software - Manual (Page 125)

Hitachi TrueCopy for z/OS user guide 125
• If DFW required is selected, the MCU will suspend the pair when DFW on the RCU is blocked. This
option is recommended if you need to maintain high MCU I/O performance.
CAUTION: The interaction of the DFW required setting and the M-VOL fence level setting can
cause a host application to fail with a permanent I/O error when attempting to update an M-VOL.
Keep track of which volume pairs have the DFW required setting and verify that the DFW to the
R-VOL is not blocked.
NOTE: The DFW to R-VOL setting does not affect the I/O performance of the M-VOLs. If one side
of cache is closed due to an RCU failure, the TC390 copy operation still uses DFW. The only
difference between not required and required is that new pairs cannot be established with the
DFW-to-R-VOL required option when one side of RCU cache is closed (the add pair operation fails).
NOTE: When you create a TC390 pair, and if you select only M-VOL for the CFW data option, the
data set which is updated by CFW in M-VOL cannot be used in R-VOL. To use this data set in R-VOL,
delete a TC390 pair, and format the data set.
• Asynchronous Parameter box consists of the following:
• CT Group: Consistency group to which the TC390A pair is assigned.
• Error Level: Error level for the TC390A pair(s)
• C/T Type: Timer type of the consistency group (System, Local or None).
• Consistency time: Consistency time of the group to which the TC390A pair is assigned
• SEQCHK: Displayed when the TC390A pair has the SEQCHK status. This status is managed by the
RCU and the MCU may not have the most current information. Always use the R-VOL pair status
information displayed at the RCU for disaster recovery.
• The Previous button changes the displayed pair status information to that of the previous Volume on the
Volume list (the Volume of the row above). The Next button changes the displayed pair status
information to that of the next Volume on the Volume list (the Volume of the row below). The Refresh
button refreshes the pair status information. The Close button closes the Pair Status window.
NOTE: The Display Filter settings can affect how Previous or Next is recognized.
The Volume list can display 256 rows at once. Therefore, the Previous and the Next buttons can be
used to display the 256 rows at once.
Creating TrueCopy volume pairs (Add Pair)
The Add Pair command creates one or more new TC390 pairs. When the Add Pair command is selected,
the Add Pair window is displayed. Use the Add Pair window to select the R-VOL, RCU, and initial copy
options for the pair(s) being created.