Active-active relationships

An active-active relationship is used to manage the synchronous replication of volume data between two sites. You must make the master volume accessible through either I/O group. The synchronizing process starts after change volumes are added to the active-active relationship.

When you work with active-active relationships, follow these guidelines and requirements:

An active-active volume is made by making an active-active relationship between the master and auxiliary volume copy.
Active-active volumes can also use change volumes, which hold earlier consistent revisions of data when changes are made. A change volume must be created for both the master volume and the auxiliary volume of the relationship.
An existing single copy volume can be converted to an active-active volume. An auxiliary volume is created at the other site and an active-active relationship between the master and auxiliary volume is made. Master and auxiliary change volumes must be added to the relationship so that the master and auxiliary copies can be synchronized. For high availability, a host access I/O group that is local to the auxiliary copy must be added.
A new active-active volume can be created by first making a master volume and an auxiliary volume and then making the active-active relationship between them.
The two volumes in an active relationship must be the same size. The change volumes must be the same size and in the same site as the associated master volume or auxiliary volume.
For ease of application management, an active-active relationship can be added to a consistency group.
Note: Membership of a consistency group is an attribute of the relationship, not the consistency group. Therefore, enter the chrcrelationship command to add or remove a relationship to or from a consistency group.
If an active-active relationship is established between two systems that have a different maximum number of volumes, only the smaller number of volumes are used. For example, system A has 10 volumes and system B has eight volumes. In an active-active relationship, only the first eight volumes are used on system A.

Active-active (HyperSwap^®) relationship group states

Table 1 describes the active-active (HyperSwap^®), relationship group states:

Table 1. Active-active (HyperSwap^®) relationship group states
Management GUI icon¹	State	Description
	Inconsistent (stopped)	Both change volumes are not defined in the relationship.
	Inconsistent (copying)	The relationship is performing initial synchronization of data to the second copy.
	Consistent (stopped)	Either the relationship was created with -sync and both change volumes are not defined or a change volume was force-deleted after the relationship synchronized.
	Consistent (copying)	The two copies are different, but resynchronization occurs when it can. During the copy, the status field is online. When the system is unable to copy, the status field shows what is preventing the copy.
	Consistent (synchronized)	The two copies both contain all completed host-write operations. The high availability failover and read pass-through options are both available.
	Idling	Manual intervention was used to restore access to a historical copy of the relationship.

Active-active relationships

Active-active (HyperSwap®) relationship group states

Active-active (HyperSwap^®) relationship group states