Hitachi VSP Gx00 series User Manual

Mode Category Description Default MCU/RCU
1106 Dynamic
Pr
ovisioning
Dynamic
Tiering
This SOM is used to monitor the page usage rate of
parity groups dened to a pool, and perform
rebalance to balance the usage rate if the rate diers
signicantly among parity groups.
Mode 1106 = ON: The usage rate is checked once a
day and the rebalance works if the rate is not even.
Mode 1106 = OFF (default): The rebalance does not
work even when the usage rate is not balanced.
The pool usage rate is determined as unbalanced
when there is 25% or more dierence between the
usage rate of each parity group in the pool and the
average.
Note: The term "page usage rate" refers to the
percentage of the number of assigned pages in each
PG compared to the total number of pages in the
pool. For HDT pools, the term "total number of
pages" is the number of pages assigned within each
specic tier.
Examples:
1. In an HDP pool, if the usage rates of PG1, PG2,
and PG3 are 50%, 40%, and 30% respectively, it
is not determined as unbalanced.
Because the average parity group usage rate is
(50%＋ 40%＋ 30%) / 3 ＝ 40% and the
dierence in the rate between each parity group
and the average is 10% at the maximum.
2. In an HDP pool, if the usage rates of PG1, PG2,
and PG3 are 80%, 40%, and 30% respectively, it
is determined as unbalanced.
Because the average parity group usage rate is
(80%＋ 40%＋ 30%) / 3 ＝ 50% and the
dierence in the rate between each parity group
and the average is 30% at the maximum.
3. In an HDT pool, if the usage rates of PG1, PG2,
and PG3 are 80% (SSD), 40% (SAS15K) and 30%
(SAS15K), it is not determined as unbalanced,
because:
■ The average parity group usage rate of Tier1
is (80%) / 1 ＝ 80% and the dierence in the
OFF -
System option modes
Appendix B: System option modes
System Administrator Guide for VSP Gx00 models and VSP Fx00 models 343

Hitachi VSP Gx00 series Specifications

General

Brand	Hitachi
Model	VSP Gx00 series
Category	Storage
Language	English