Hitachi VSP G400 - Page 324

Mode Category Description Default MCU/RCU
898 Dynamic
Tiering
By the combination of SOM 898 and 897 setting, the
e
xpansion width of Tier Range upper I/O value
(IOPH) can be changed as follows.
Mode 898 = ON:
■
SOM 897 is OFF: 110%+1IO
■
SOM 897 is ON: 110%+2IO
Mode 898 = OFF (default):
■
SOM 897 is OFF: 110%+5IO (default)
■
SOM 897 is ON: 110%+0IO
By setting the SOMs to ON to lower the upper limit
for each tier, the gray zone between other tiers
becomes narrow and the frequency of page
allocation increases.
Notes:
1. Apply this SOM when the usage of upper tier is
low and that of lower tier is high.
2. This SOM must be used with SOM 897.
3. Narrowing the gray zone increases the number
of pages to migrate between tiers per
relocation.
4. When Tier1 is SSD while SOM 901 is set to ON,
the eect of SOM 897 and 898 to the gray zone
of Tier1 and Tier2 is disabled and the SOM 901
setting is enabled instead. In addition, the
settings of SOM 897 and 898 are eective for
Tier2 and Tier3.
For more details about the interactions between
SOMs 897, 898, and 901, contact customer support
(see SOM897_898_901 sheet).
OFF -
System option modes
Appendix B: System option modes
System Administrator Guide for VSP Gx00 models and VSP Fx00 models 324