3.15 Online Backup and Restoration Using Proxy Volume

This subsection describes the modes for online backup and instant restore of local volumes and shared volumes through use of snapshots by GDS Snapshot proxy volumes.

There are two online backup methods: one uses the function as "1.5.1 Snapshot by Synchronization" and the other uses the function as "1.5.3 Instant Snapshot by OPC."

By cooperation with the following functions, backup and restore processing that do not impose the load on the server or SAN become possible.

Advanced Copy function of ETERNUS Disk storage system
EC (including REC for 4.3A30 or later) or OPC (including QuickOPC for 4.3A30 or later)
Copy function of Dell EMC storage units (not supported in this version)
Dell EMC TimeFinder or Dell EMC SRDF

The following table shows backup and restore methods and their features.

Operation	Disk Unit's Copy Function	Master Configuration (*2)	Proxy Configuration (*2)	Feature
Backup(Sync)	-	single mirror mirror + stripe mirror + concat	single mirror mirror + stripe mirror + concat	With synchronized masters and proxies, snapshots are created simply by parting the proxies. By use of the JRM for proxies, high-speed resynchronization is executable for snapshot re-creation. Striping and concatenating masters are possible. Mirroring, striping and concatenating proxies are possible.
	EC REC [4.3A30 or later] TimeFinder (1) SRDF (1)	single mirror	single	With synchronized masters and proxies, snapshots are created simply by parting the proxies. By use of a disk unit's copy function, snapshot creation that does not impose the load on the server or SAN is possible. By use of a disk unit's incremental copy function, high-speed resynchronization that does not impose the load on the server or the SAN is performed for snapshot re-creation.
	OPC QuickOPC [4.3A30 or later]	single mirror	single	With synchronized masters and proxies, snapshots are created simply by parting the proxies. By use of a disk unit's copy function, snapshot creation that does not impose the load on the server or SAN is possible.
Backup(OPC)	OPC QuickOPC [4.3A30 or later]	single mirror	single	There is no need to synchronize masters and proxies before creating snapshots, and backups can be created any time without scheduling in advance. By use of a disk unit's copy function, snapshot creation that does not impose the load on the server or SAN is possible.
Restore	-	single mirror mirror + stripe mirror + concat	single mirror mirror + stripe mirror + concat	By use of the JRM for proxies, high-speed restore is possible. Striping and concatenating masters are possible. Striping and concatenating proxies are possible.
Restore	OPC QuickOPC [4.3A30 or later]	single mirror	single mirror	By use of a disk unit's copy function, restore that does not impose the server or SAN is possible.

(*1) Not supported in this version

(*2) In the table above, configurations indicate objects as follows.

Configuration	Description
single	This configuration means any one of the following objects. A single volume created in a single disk A mirror group not hierarchized, with the multiplicity of one A volume created in a mirror group not hierarchized, with the multiplicity of one
mirror	This configuration means either the following objects. A mirror group not hierarchized, with the multiplicity of two and higher A mirror volume created in a mirror group not hierarchized, with the multiplicity of two and higher
mirror + stripe	This configuration means either the following objects. A mirror group to which one or more stripe groups are connected A volume created in a mirror group to which one or more stripe groups are connected
mirror + concat	This configuration means either the following objects. A mirror group to which one or more concatenation groups are connected A volume created in a mirror group to which one or more concatenation groups are connected

For details on backup and restore by cooperation with copy functions of disk units (EC, OPC, TimeFinder, SRDF), see "1.5.2 Snapshot Function with No Load to Server/SAN," "A.8 Using Advanced Copy Function in Proxy Configuration," "3.18 Instant Snapshot by OPC" and "3.19 Using Dell EMC TimeFinder or Dell EMC SRDF in Proxy Configuration."