Hitachi Universal Storage Platform V Reference Manual page 65

Mode Category
564 TrueCopy for z/OS
Hitachi Universal Storage Platform V/VM User and Reference Guide
Prevents the performance improvement logic (early release of
Extent exclusion) from being performed.
Mode 564 = ON:
1. Extent exclusion wait tends to take place for the Write
processing on another record in the same extent, so that
the performance may degrade.
2. Same as #1, though extent exclusion wait tends to take
place for the Write processing on the same record, the rate
of performance degradation is lower than that of RIO wait.
Mode 564 = OFF (default):
1. Extent exclusion wait tends not to take place for the Write
processing on another record in the same extent, so that
the performance is improved.
2. Though extent exclusion wait tends not to take place for
the Write processing on the same record, RIO wait tends to
take place so that the possibility of performance
degradation may be higher than that of before the
performance improvement logic.
Note: Apply this option when the performance improvement
logic (early release of Extent exclusion) needs to be
prevented.
For 60-04-12-00/00 or higher, the following combinations of
modes 574 and 564 are available.
When early release of Extent exclusion is enabled:
Mode 574 = ON, Mode 564 = OFF
1. Extent exclusion wait tends not to take place for the Write
processing on another record in the same extent, so that
the performance is improved.
2. Though extent exclusion wait tends not to take place for
the Write processing on the same record, RIO wait tends to
take place so that the possibility of performance
degradation may be higher than that of before the
performance improvement logic.
When early release of Extent exclusion is disabled:
Mode 574 = ON, Mode 564 = ON
Mode 574 = OFF, Mode 64 = ON
Mode 574 = OFF, Mode 564 = OFF
3. Extent exclusion wait tends to take place for the Write
processing on another record in the same extent, so that
the performance may degrade.
4. Same as #3, though extent exclusion wait tends to take
place for the Write processing on the same record, the rate
of performance degradation is lower than that of RIO wait.
Note:
This option is applied when the performance improvement
logic (early release of Extent exclusion) needs to be
prevented.
If mode 574 is simultaneously used with this option,
performance improvement or degradation varies depending
on the combination of mode settings.
For 60-04-12 or higher, refer to the SOM574 document.
Functional and Operational Characteristics
Function Default MCU/RCU
OFF MCU
3-21