Splitting a mirrored aggregate removes the relationship between its two plexes and creates two independent unmirrored aggregates. After splitting, both the aggregates come online.
Before splitting, a mirrored aggregate or traditional volume has two plexes, plex0 and plex1. After splitting, the new unmirrored aggregate with the new name has one plex, plex0. The new unmirrored aggregate with the original name also has one plex, either plex0 or plex1.
The plex name for an unmirrored aggregate is unimportant because the aggregate has only one plex. If you use SyncMirror to mirror one of these unmirrored aggregates, the resulting plex names will always be plex0 and plex1.
plexname is the name of one of the plexes in the mirrored aggregate.
new_aggr is the name of the new aggregate that would be created.
After splitting, there are two unmirrored aggregates, aggr0 and aggrNew.