Silicon Graphics InfiniteStorage 4000 Series, Configuring And Maintaining

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122 How Asynchronous Mirroring Works
You can use asynchronous mirroring for these functions:

Disaster recovery
– You can replicate data from one site to another site, which
provides an exact duplicate at the remote (secondary) site. If the primary site
fails, you can use mirrored data at the remote site for failover and recovery. You
can then shift storage operations to the remote site for continued operation of all
of the services that are usually provided by the primary site.

Data vaulting and data availability
– You can send data off site where it can be
protected. You can then use the offset copy for testing or to act as a source for a
full backup to avoid interrupting operations at the primary site.

Two-way data protection
– You can have two storage arrays back up each other
by duplicating critical volumes on each storage array to volumes on the other
storage array. This action lets each storage array recover data from the other
storage array in the event of any service interruptions.
How
Asynchronous
Mirroring Works When you set up asynchronous mirroring, you create a one-to-one relationship
between the volumes in a remote-mirrored pair. The remote-mirrored pair consists of
a
primary volume
on a local storage array and a
secondary volume
on a storage array
at another site. The primary-secondary role is defined in an asynchronous mirror
group. Mirrored relationships are created by adding a volume to the primary
asynchronous mirror group and adding the corresponding volume to the secondary
asynchronous mirror group on the remote storage array. The maximum numbers of
supported asynchronous mirrored pairs are listed in the following table.
NOTE
Remember, most mirror operations (such as creating relationships,
synchronization settings, and mirroring role) are managed through an asynchronous
mirror group.
Table 22 Maximum Number of Defined Mirrors
The Asynchronous Mirroring premium feature is supported only on E2660 and E5460
configurations.
The primary volume is the volume that accepts host I/O activity and stores application
data. When the mirror relationship is first created, data from the primary volume is
copied in its entirety to the secondary volume. This process is known as a
full
synchronization
and is directed by the controller owner of the primary volume.
During a full synchronization, the primary volume remains fully accessible for all
normal I/O operations.
Controller Model Per Storage Array
Per Asynchronous
Mirroring Group
E2660 32 32
E5460 128 64