Hitachi Universal Storage Platform VM - Manual (Page 66)

3-22 Functional and Operational Characteristics
Hitachi Universal Storage Platform V/VM User and Reference Guide
Mode Category Function Default MCU/RCU
573 TrueCopy for z/OS,
ShadowImage for
z/OS For the CU emulation type 2105/2107, specifying the
CASCADE option for the ICKDSF ESTPAIR command is
allowed.
Mode 573 = ON: The ESTPAIR CASCADE option is allowed.
Mode 573 = OFF (default): The ESTPAIR CASCADE option is
not allowed. (When specified, the option is rejected.)
Note:
1. When CU emulation type is 2105/2107, this mode is
applied in the case where pair creation in TCz – SIz
cascading configuration in the ICKDSF environment fails
with the following message output.
Message: ICK30111I DEVICE SPECIFIED IS THE
SECONDARY OF A DUPLEX OR PPRC PAIR
2. The CASCADE option can be specified in the TSO
environment also.
3. Although the CASCADE option can be specified for the
ESTPAIR command, the PPRC-XD function is not supported.
4. Perform thorough pre-check for any influence on
GDPS/PPRC.
5. The SOM must be enabled only when the CASCADE option
is specified for the ESTPAIR command for the CU emulation
type 2105/2107.
OFF MCU/RCU
The unit
where TCz
and SIz in
a
cascading
config.
use the
same
volume.
585 Copy-on-Write
Snapshot At the time of page allocation during the host write operation
of COW Snapshot, HDD blocks are sequentially allocated from
the top, aiming for performance improvement in destaging to
the pool by achieving efficient HDD access.
Mode 585 = ON: Page allocation is performed in random
order.
Mode 585 = OFF (default): Page allocation is performed in
sequential order.
Note:
1. Set this mode to ON when you want to deactivate the new
HDD block allocation method that is supported in USP V/VM
microcode 60-05-xx-00/00.
2. The action of this mode has been reversed in the USP
V/VM, so that the desired functionality is achieved with the
mode set to OFF (default). For TagmaStore USP/NSC the
desired functionality is achieved with the mode set to ON.
Caution: Turning this mode to ON for USP V/VM will
deactivate this functionality.
3. As the HDD blocks are allocated in random order, a pool
can become bottleneck, and performance may be affected.
4. Even though this mode is ON, pools created when this
mode was OFF continue to operate on the new logic
(function enabling HDD blocks to be allocated from the
top), so all pools created while this mode was OFF need to
be deleted.
OFF –