Understanding the root aggregate

The root aggregate contains the root volume, which contains special directories and configuration files that help you administer the storage system.

The following facts apply to the root aggregate:

• Starting with Data ONTAP 8.1, new systems are shipped with the root volume in a 64-bit root aggregate.
• By default, the storage system is set up to use a hard disk drive (HDD) aggregate for the root aggregate.

  When no HDDs are available, the system is set up to use a solid-state drive (SSD) aggregate for the root aggregate. If you want to change the root aggregate, you can choose either an HDD aggregate or an SSD aggregate to be the root aggregate (aggr options aggr_name root), provided that the corresponding type of disk drives is available on the system.

• A Flash Pool aggregate (an aggregate that contains both HDDs and SSDs) can be used as the root aggregate.
  Attention: If you revert or downgrade to Data ONTAP 8.1 or earlier with a Flash Pool aggregate configured as your root aggregate, your system will not boot.