How Snapshot Works; Volume Pairs - P-Vols And V-Vols - Hitachi AMS2100 User Manual

How SnapShot works

Volume pairs — P-VOLs and V-VOLs
Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide
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Figure 1-1: SnapShot functional component
The following sections describe how these components work
together.
SnapShot creates a virtual duplicate volume of another volume. This
volume "pair" is created when you:
• Select a volume that you want to replicate
• Identify another volume that will contain the copy
• Associate the primary and secondary volumes
• Create a snapshot of primary volume data in the virtual
(secondary) volume.
Once a snapshot is made, it remains unchanged until a new snapshot
instruction is issued. At that time, the new image replaces the
previous image.
A volume pair is a relationship established by SnapShot between two
volumes. A pair consists of a production volume, which contains the
original data and is called the primary volume (P-VOL), and from 1
to 32 virtual volumes (V-VOLs), which contain virtual copies of the P-
VOL. The P-VOL and its V-VOL(s) are located in the same array.
SnapShot overview
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