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Asynchronous Mirroring feature

Asynchronous Mirroring provides a controller-level, firmware-based mechanism for data replication between a local site and a remote site. Replication is managed on a per-volume basis, allowing a storage administrator to associate a distinct remote mirrored volume with every primary volume on a given storage array.

For Asynchronous Mirroring, the local storage array and the remote storage array can run different versions of firmware. The minimum firmware version supported is SANtricity firmware version 7.84.

This table shows the maximum number of defined mirrors that can be defined for each controller model.

Storage Array Maximum Number of Defined Mirrors
EF560 controller-drive tray Up to 128
E5600 controller-drive tray Up to 128
EF550 controller-drive tray Up to 128
E5500 controller-drive tray Up to 128
E2700 controller-drive tray Up to 32

Asynchronous mirror groups allow you to manage the synchronization process as a set to create a crash-consistent data-set on the remote storage array. Point-in-time images are used on the primary volume and the secondary volume to batch the resynchronization process. (A data repository volume is required for each mirrored volume.)

Note: When creating a mirrored pair with FIPS drives, ensure that the mirrored pair has the same level of security capabilities. For example, FDE drives provide security, but do not contain the same security level as FIPS drives.

When write operations are performed to the primary volume of an asynchronous mirrored pair, the modified data region of the primary volume is tracked. Periodically, the firmware creates a new point-in-time image of the primary volume and sends the changed data regions to the secondary volume. When data synchronization completes, the system uses the point-in-time images on the secondary volume to ensure that the data is maintained in a consistent state during subsequent synchronization operations to the secondary volume.

The automatic cycle in an active asynchronous mirroring session works as follows to maintain data at a remote site to be a point-in-time consistent copy of data at the local site.
  1. Asynchronous mirror groups consisting of volumes are created at the local site and volumes at the remote site.
  2. Increments of consistent data are sent to the remote site.
  3. Point-in-time copy operations are performed at the remote site.
The steps are repeated according to the defined synchronization intervals.
Note: Asynchronous Mirroring supports both iSCSI and Fibre Channel connections between storage arrays.
Note: Asynchronous Mirroring supports standard volumes in disk pools and volume groups, and thin volumes in disk pools for mirrored volume types.