https://library.netapp.com/ecmdocs/ECMP1196890/html/man1/na_aggr.1.html

aggr split aggrname/plexname new_aggrname

Removes plexname from a mirrored aggregate and creates a new unmirrored aggregate named

new_aggrname that contains the plex. The original mirrored aggregate becomes unmirrored. The plex to be split from the original aggregate must be functional (not partial), but it could be inactive, resyncing, or out-ofdate.

Aggr split can therefore be used to gain access to a plex that is not up to date with respect to its partner

plex, if its partner plex is currently failed.

If the aggregate in which plexname resides is embedded in a traditional volume, aggr split behaves identically to vol split. The new aggregate is embedded in a new traditional volume of the same name.

The aggregate in which plexname resides must contain exactly one flexible volume, aggr split will by default rename the flexible volume image in the split-off plex to be the same as the new aggregate.

If the original aggregate is restricted at the time of the split, the resulting aggregate will also be restricted. If the restricted aggregate is hosting flexible volumes, they are not renamed at the time of the split. Flexible volumes will be renamed later, when the name conflict is detected while bringing an aggregate online. Flexible volumes in the aggregate that is brought online first keep their names. That aggregate can be either the original aggregate, or the aggregate resulting from the split. When the other aggregate is brought online later, flexible volumes in that aggregate will be renamed.

If the plex of an aggregate embedded within a traditional volume is offline at the time of the split, the resulting aggregate will be offline. When splitting a plex from an aggregate that hosts flexible volumes, if that plex is offline, but the aggregate is online, the resulting aggregate will come online, and its flexible volumes will be renamed. It is not allowed to split a plex from an offline aggregate.

A split mirror can be joined back together via the -v option to aggr mirror.