6.6 Online Backup and Instant Restore through Proxy Volume

This subsection describes the procedures 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) or OPC
Copy function of Dell EMC storage units
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 (*1)	Proxy Configuration (*1)	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 TimeFinder SRDF	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	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	single mirror stripe concat	single stripe concat	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. Striping and concatenating masters are possible. Striping and concatenating proxies are 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	single mirror stripe concat	single mirror stripe concat	By use of a disk unit's copy function, restore that does not impose the server or SAN is possible. Striping and concatenating masters are possible. Striping and concatenating proxies are possible.

(*1) 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 (excepting when using TimeFinder or SRDF) A mirror group not hierarchized, with the multiplicity of one A volume created in a mirror group not hierarchized, with the multiplicity of one (excepting when using TimeFinder or SRDF)
mirror	This configuration means either of 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 (excepting when using TimeFinder or SRDF)
mirror + stripe	This configuration means either of 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 of 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.
stripe	A volume created in a stripe group not hierarchized.
concat	A volume created in a concatenation group not hierarchized.

For details on backup and restore by cooperation with copy functions of disk units (EC, OPC, TimeFinder and SRDF), see "1.5.2 Snapshot Function with No Load to the Server/SAN," "A.2.23 Using the Advanced Copy Function in a Proxy Configuration," "A.2.24 Instant Snapshot by OPC" and "A.2.27 Using Dell EMC TimeFinder or Dell EMC SRDF in a Proxy Configuration."