Local replication with clones (ETERNUS DX/AF, Symmetrix/VMAX3)

The following functions are available for local replication with clones:

• for ETERNUS DX/AF, the QuickOPC function

• For ETERNUS DX/AF, the EC (Equivalent Copy) function

• For Symmetrix/VMAX3, the TimeFinder/Clone function

  On VMAX3, TimeFinder/Clone is implemented compatibly by SHC-OSD in the previous functional scope with the previous interfaces. SYMAPI emulates TimeFinder/Clone via TimeFinder SnapVX. The statements in this chapter therefore also apply for VMAX3.

Coexistence of QuickOPC and EC

On ETERNUS DX/AF and for new applications, the usage of the more flexible and strategic QuickOPC is recommended, see section “Clone units with QuickOPC, EC and TimeFinder/Clone” in "Clone unit with complete copy of the original data".

Clones mirrored with QuickOPC or EC can exist in parallel on an ETERNUS DX/AF storage system. The parallel mirroring of single volumes is not possible. The parallel usage of QuickOPC and EC is only recommended for a transitional phase in which some pubsets are mirrored with QuickOPC and others with EC.

You can specify which clone function to use for the START-CLONE-SESSION command centrally and globally in the SHC-OSD parameter file and selectively in the command itself with the CLONE-TYPE parameter. An explicit specification in the command overweighs the settings in the SHC-OSD parameter file.

Overview on local replication

The commands for the QuickOPC, EC and TimeFinder/Clone functions control replication functions which assign one or more clone units to an original unit and manage the clone pairs (clone sessions) created. The SHOW commands display their current processing status, the status of the clone sessions and the configuration.

The functions execute in a similar manner and are controlled in BS2000 by SHC-OSD with the same commands. The functions are consequently (to some degree) presented in parallel in this chapter:

Section	Relevant for
QuickOPC (ETERNUS DX/AF)	ETERNUS DX/AF
Equivalent Copy (EC, ETERNUS DX/AF)	ETERNUS DX/AF
TimeFinder/Clone (Symmetrix/VMAX3)	Symmetrix/VMAX3
Status of the clone session and of the devices	All functions and storage systems
Working with clones	All functions and storage systems
Utilization concepts for clones	All functions and storage systems
QuickOPC/EC and REC (ETERNUS DX/AF)	ETERNUS DX/AF
TimeFinder/Clone and SRDF (Symmetrix/VMAX3)	Symmetrix/VMAX3

Commands for QuickOPC (ETERNUS DX/AF) EC (ETERNUS DX/AF) and TimeFinder/Clone (Symmetrix/VMAX3)

Command	Function
ACTIVATE-CLONE	Activates a clone pair (EC and TimeFinder/Clone)
RESTART-CLONE-SESSION	Re-creating a clone pair
RESTORE-FROM-CLONE	Reconstructs an original from a clone unit
SHOW-CLONE-SESSION-STATUS	Displays the status of clone pairs
SHOW-STORAGE-CONFIGURATION	Displays the configuration (ETERNUS DX/AF)
SHOW-STORAGE-DEVICE-CONFIG	Displays device configuration (ETERNUS DX/AF)
SHOW-SYMMETRIX-CONFIGURATION	Displays the configuration (Symmetrix/VMAX3)
SHOW-SYMMETRIX-DEVICE-CONFIG	Displays device configuration (Symmetrix/VMAX3)
START-CLONE-SESSION	Creates a clone pair
STOP-CLONE-SESSION	Cancels a clone pair
SWAP-CLONE-SESSION	Swaps original and clone attributes of a clone pair (ETERNUS DX/AF with EC)