A SyncMirror aggregate has two plexes. This setup provides a high level of data availability because the two plexes are physically separated.
For a system using disks, the two plexes are on different shelves connected to the system with separate cables and adapters. Each plex has its own collection of spare disks. For a system using third-party storage, the plexes are on separate sets of array LUNs, either on one storage array or on separate storage arrays.
Note: You cannot set up SyncMirror with disks in one plex and array LUNs in the other plex.
Physical separation of the plexes protects against data loss if one of the shelves or the storage array becomes unavailable. The unaffected plex continues to serve data while you fix the cause of the failure. Once fixed, the two plexes can be resynchronized.
Another advantage of mirrored plexes is faster rebuild time.
In contrast, if an aggregate using SnapMirror
for replication becomes unavailable, you can use one of the following options to access the data on the SnapMirror
- The SnapMirror destination cannot automatically take over the file serving functions. However, you can manually set the SnapMirror destination to allow read-write access to the data.
- You can restore the data from the SnapMirror destination to the primary (source) storage system.
An aggregate that is mirrored using SyncMirror
requires twice as much storage as an unmirrored aggregate. Each of the two plexes requires an independent set of disks or array LUNs. For example, you need 2,880 GB of disk space to mirror a 1,440-GB aggregate—1,440 GB for each plex of the mirrored aggregate.