Hitachi VSP G400 User Guide

Snapshot tree components
A snapshot tree contains the following volumes.
Volume type Volumes that can be used Description
Root Logical volume (LDEV)
Volume (L1 pair of the P-VOL)
in the top layer of a snapshot
tree.
The logical volume of the P-VOL
contains DP-VOLs (V-VOL of
which provisioning type is
Dynamic Provisioning).
Node DP-VOL
Volumes located between the
root volume and leaf volumes.
S-VOL of the root volume (or
another node volume), and the
P-VOL of a leaf volume (or
another node volume).
Leaf DP-VOL
Volumes in the bottom layer of
a snapshot tree.
S-VOL of the root volume or a
node volume, which is not a P-
VOL of any pair.
Consistency and snapshot groups
Consistency groups and snapshot groups are groups of pairs for which you
can simultaneously perform pair tasks on all pairs within the group.
A consistency group can include Thin Image (HTI), ShadowImage (SI), and
ShadowImage for Mainframe (SIz) pairs. Use consistency groups to split the
Thin Image pairs that are defined in the group. Splitting the pairs using the
group assures data consistency at the time the VSP family storage system
receives the request.
A snapshot group is a group of only Thin Image pairs. Use consistency or
snapshot groups to perform Thin Image tasks on all of the pairs within the
group. You define Thin Image pairs to a snapshot group when you create the
pairs.
The following table shows the differences between consistency groups and
snapshot groups.
Item
Consistency group Snapshot group
Pair limit per group 8,192 8,192
Limit 2,048 2,048
Data consistency Guaranteed Not guaranteed
Software application from which you can define pairs HTI, SI, and SIz HTI
20 Overview of Thin Image
Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Hitachi VSP G400 Specifications

General

Brand	Hitachi
Model	VSP G400
Category	Storage
Language	English