Hitachi VSP G400 System Administration Guide

Mode Category Description Default MCU/RCU
The pool usage rate is determined as unbalanced when there
is 25% or more difference between the usage rate of each
parity group in the pool and the average.
Note: For HDT pools (including those with active flash
attribute), the average of parity group usage rates is
calculated per 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 difference 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 difference 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 difference in the rate
between the parity group and the average is 0%.
• The average parity group usage rate of Tier2 is
(40%＋ 30%) / 2 ＝ 35% and the difference in the
rate between the parity group and the average is
5% at the maximum.
Note: This SOM is applied when balancing the usage rate is
required at a customer site where the usage rate is not even.
1115
Deduplication
and Compression
When this SOM is set to ON, data is initialized without using
metadata at LDEV format for a virtual volume with Capacity
Saving enabled.
Mode 1115 = ON: When LDEV format is performed for a
virtual volume whose capacity saving setting is Compression,
the data is initialized without using the metadata.
Mode 1115 = OFF (default): When LDEV format is
performed for a virtual volume whose capacity saving setting
is Compression, normal formatting is performed, but if one of
the following conditions is met, the data is initialized without
using metadata.
• There is a pinned slot.
• The capacity saving status is “Failed”.
• The virtual volume is blocked (Normal restore cannot be
performed).
Notes:
1. This SOM is applied to recover a blocked pool volume in
a pool to which a virtual volume whose capacity saving
setting is Compression belongs.
OFF -
System option modes 383
System Administrator Guide for VSP Gx00 models and VSP Fx00 models

Hitachi VSP G400 Specifications

General

Brand	Hitachi
Model	VSP G400
Category	Storage
Language	English