User guide
System option modes B–27
Hitachi Unified Storage VM Block Module Hardware User Guide
917 Dynamic
Provisioning,
Dynamic
Tiering
The mode is used to switch the method to migrate data
at rebalancing.
Mode 917 = ON (default):
Page usage rate is averaged among parity groups or
external volume groups where pool volumes are defined.
Mode 917 = OFF:
Page usage rate is averaged among pool volumes
without considering parity groups or external volume
groups.
Note:
1. The mode is applied when multiple LDEVs are
created in a parity group or in an external volume
group.
2. If the mode setting is changed during pool shrink,
the shrink processing may fail.
3. When the mode is set to OFF, the processing to the
average page usage rate among pool volumes in a
parity group or in an external volume group works;
therefore, the drive workload becomes high because
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.
ON .
Mode Category Description Default
MCU/
RCU