Mode Category Description Default MCU/RCU
901 Dynamic
Tiering
By setting this SOM to ON or OFF, the page allocation
method of Tier Le
vel ALL when the drive type of tier1
is SSD changes as follows.
Mode 901 = ON: For tier1 (drive type is SSD), pages
are allocated until the capacity reaches the limit.
Without consideration of exceeding performance
limitation, allocation is done from highly loaded
pages until reaching the capacity limit
When the capacity of tier1 reaches the threshold
value, the minimum value of the tier range is set to
the starting value of the lower IOPH zone, and the
maximum value of the lower tier range is set to the
boundary value.
Mode 901 = OFF (default): For tier1 (drive type is
SSD), page allocation is performed based on
performance potential limitation. With consideration
of exceeding performance limitation, allocation is
done from highly loaded pages but at the point when
the performance limitation is reached, pages are not
allocated any more even there is free space.
When the capacity of tier1 reaches the threshold
value, the minimum value of the tier range is set to
the boundary value, and the maximum value of the
lower tier range is set to a value of boundary-value ×
110% + 5 [IOPH].
Notes:
1. This SOM is applied when pages with the
maximum capacity need to be allocated to tier1
(drive type is SSD) with Dynamic Tiering.
2. When Tier1 is SSD while SOM 901 is set to ON,
the eect 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 eective for
Tier2 and Tier3.
3. The following is recommended when applying
SOM 901.
actual I/O value (total number of I/Os of all
tiering policies) < performance potential value
of Tier1* × 0.6
* The performance potential value of Tier1
displayed on Monitor information by using Dx-
ray.
OFF -
System option modes
Appendix B: System option modes
System Administrator Guide for VSP Gx00 models and VSP Fx00 models 327
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