HP StorageWorks Continuous Access XP user guide for the XP10000/XP12000 (December 2005)

94 Continuous Access XP for the XP10000/XP12000
• No Copy: The initial copy operation is not performed. The MCU performs update copy operations as
needed.
CAUTION: Ensure that the P-VOL and S-VOL are already identical when using this setting.
Initial Copy Pace: Maximum number of tracks (1-15) that can be copied at one time by the Continuous
Access XP initial copy operation before the MCU accepts another host request for that P-VOL. A high
setting (for example, 15 tracks) speeds up the initial copy operation, but may affect the disk array’s I/O
performance if the P-VOL experiences high write I/O activity. A lower setting (for example, 3 tracks) slows
down the initial copy operation to minimize impact on the disk array’s I/O performance.
Priority: Order in which initial copy operations are performed if the number of requested initial copy
operations is greater than the maximum initial copy activity setting on the RCU Option pane (see
”Registering RCUs (Add RCU)” on page 64). The highest priority is 1, and the lowest priority is 256
(current default = 32). Use the Continuous Access XP initial copy priority option to spread initial copy
operations across disk array groups and disk array domains (ACP pairs) to reduce initial copy time and
host I/O contention.
For example, suppose the maximum initial copy activity setting is four, and you add six Continuous Access
XP pairs at one time (for LUNs 00 through 05) with the initial copy priority set as follows:
Difference Management: Measurement method Continuous Access XP uses to manage differential data for
the pair: Auto, Cylinder, or Track. The default is Auto. When you select Auto, either Cylinder or Track is
selected depending on basic size of the logical unit (LU).
Asynchronous parameters
C/T Group: Consistency group for new pairs (Async only). All Continuous Access XP Asynchronous pairs
must be assigned to a consistency group.
Error level: Error level for Continuous Access XP Async pairs.
• Group: When the specified pair is suspended, all Continuous Access XP Async pairs in the same group
are suspended, even if the failure affects only that pair and not the entire group.
Select Group for all Continuous Access XP Async volumes essential to disaster recovery.
• LU: If the failure affects only the specified pair, only that pair is suspended. A failure that affects an
entire group always results in suspension of all pairs in the group and all other affected Continuous
Access XP pairs.
Suspended Continuous Access XP Async S-VOLs with LU should not be used for disaster recovery.
Splitting Continuous Access XP pairs (Pairsplit-r)
Use the Pairsplit-r command to split Continuous Access XP pairs. When the Pairsplit-r command is
selected, the Pairsplit-r pane appears. Use the Pairsplit-r pane to select Pairsplit-r options for the pairs. You
can split a Continuous Access XP pair only after the initial copy operation is complete. For further
P-VOL of pair Priority
The MCU starts initial copy operations for LUNs 03, 05,
00, and 04 immediately, starts LUN 01 when one of the
first four initial copy operations is complete, and starts LUN
02 when the next initial copy operation is complete. If more
Continuous Access XP pairs are created, the MCU also
prioritizes initial copy operations by time requested, so all
pairs in the first group are started before any pair in the
next group is started.
LUN 03 1
LUN 05 2
LUN 00 3
LUN 04 4
LUN 01, 02 5