Mode Category Description Default
MCU/R
CU
the migration source and target are in the same
parity group or external volume group.
4. When pool shrink is performed per pool VOL from a
parity group with multiple pool VOLs defined (or from
an external volume group) while the mode is set to
ON, the pool shrink takes longer than when the mode
is set to OFF.
930 Dynamic
Provisioning,
Hitachi Thin
Image
When the mode is set to ON, all of the zero data page
reclamation operations in processing are stopped. (Also
the zero data page reclamation cannot be started.)
* Zero data page reclamation by WriteSame and UNMAP
functions, and IO synchronous page reclamation are not
disabled.
Mode 930 = ON:
All of the zero data page reclamation operations in
processing are stopped at once. (Also the zero data
reclamation cannot be newly started.)
Mode 930 = OFF (default):
The zero data page reclamation is performed.
See sheet "SOM930" for relationship with SOM755 and
SOM859.
Note:
1. The mode is applied when stopping or disabling zero
data page reclamation by user request is required.
2. When the mode is set to ON, the zero data page
reclamation does not work at all.
¢
Zero data page reclamation by Write Same and
UNMAP, and IO synchronous page reclamation
can work.
3. When downgrading micro-program to a version that
does not support the mode while the mode is set to
ON, set the mode to OFF after the downgrade
¢
Because the zero data page reclamation does not
work at all while the mode is set to ON.
4. The mode is related to SOM755 and SOM859.
Table B-2 Mode 269: Storage Navigator Operations
Operation Target of Operation Mode 269 ON Mode 269 OFF
VLL (CVS) All LDEVs in a PG No format No format
VLL (CVS) Some LDEVs in a PG No format No format
Format PG is specified No operation No operation
Format All LDEVs in a PG Low speed Low speed
Format Some LDEVs in a PG Low speed Low speed
System option modes
B-25
Hitachi Unified Storage VM Block Module Hardware User Guide
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