Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

Performing TrueCopy for z/OS Pair Operations 6-9
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Initial Copy Options
When you add new TrueCopy pairs, you select the initial copy options on the
Add Pair dialog box. After a pair has been added (i.e., the add pair operation
has started), you cannot change the initial copy options, unless you release
and then restart the pair.
Initial Copy. Specifies the initial copy mode for the new pair(s).
• If Entire Volume is selected, the initial copy operation will copy the data in
all tracks on the M-VOL (except diagnostic and unassigned alternate tracks)
to the R-VOL. This setting is functionally equivalent to the MODE=COPY
parameter for the CESTPAIR command.
• If None is selected, the initial copy operation will not be performed. The MCU
will begin performing update copy operations as needed. This setting is
functionally equivalent to the MODE=NOCOPY parameter for the CESTPAIR
command. Caution: The user must ensure that the M-VOL and R-VOL are
already identical when using this setting.
Copy Pace. Specifies the maximum number of tracks that can be copied at
one time by the TCz initial copy operation before the MCU accepts another
host request:
• 15 Tracks: speeds up the initial copy operation but may affect the storage
system’s I/O performance if the M-VOL is experiencing high write I/O activity.
This setting is functionally equivalent to the PACE=2-255 parameter for the
CESTPAIR TSO command.
• 3 Tracks: slows down the initial copy operation to minimize the impact of
the initial copy operation on the storage system’s I/O performance. This
setting is functionally equivalent to the PACE=1 parameter for the CESTPAIR
command.
Priority. Specifies the order in which the initial copy operations will be
performed, if the number of requested initial copy operations is greater than
the maximum initial copy activities setting on the System Option window.
The highest priority is 1, and the lowest priority is 256 (current default = 32).
The TCz initial copy priority option can be used to spread initial copy
operations across array groups and/or array domains (ACP pairs) to reduce
initial copy time as well as host I/O contention.
Example:
Let’s say the maximum initial copy activities setting is 4, and you
add 6 TCz pairs at the same time (for LDEVs 00 through 05) with the initial
copy priority set as follows:
M-VOL of TCz pair Priority
LDEV 03 1
LDEV 05 2
LDEV 00 3
LDEV 04 4
The MCU will start the initial copy operations for
LDEVs 03, 05, 00, and 04 immediately, then
start LDEV 01 when one of the first four initial
copy operations is complete, and then start LDEV
02 when the next initial copy operation is