How unmirrored aggregates work
Unless you are using SyncMirror, all of your aggregates are unmirrored. Unmirrored aggregates have only one plex (copy of their data), which contains all of the RAID groups belonging to that aggregate.
The following diagram shows an unmirrored aggregate composed of disks, with its one plex. The aggregate has four RAID groups: rg0, rg1, rg2, and rg3. Each RAID group has 6 data disks, one parity disk, and one dparity (double parity) disk. All disks used by the aggregate come from the same pool, pool0.
The following diagram shows an unmirrored aggregate with array LUNs, with its one plex. It has two RAID groups, rg0 and rg1. All array LUNs used by the aggregate come from the same pool, pool0.