Understanding RAID drive types

Data ONTAP classifies drives (or, for partitioned drives, partitions) as one of four types for RAID: data, hot spare, parity, or dParity. You manage disks differently depending on whether they are spare or being used in an aggregate.

The RAID type is determined by how RAID is using a drive or partition; it is different from the Data ONTAP disk type.

You cannot affect the RAID type for a drive. The RAID type is displayed in the Position column for many storage commands.

For drives using root-data partitioning and SSDs in storage pools, a single drive might be used in multiple ways for RAID. For example, the root partition of a partitioned drive might be a spare partition, whereas the data partition might be being used for parity. For this reason, the RAID drive type for partitioned drives and SSDs in storage pools is displayed simply as shared.

Data disk
Holds data stored on behalf of clients within RAID groups (and any data generated about the state of the storage system as a result of a malfunction).
Spare disk
Does not hold usable data, but is available to be added to a RAID group in an aggregate. Any functioning disk that is not assigned to an aggregate but is assigned to a system functions as a hot spare disk.
Parity disk
Stores row parity information that is used for data reconstruction when a single disk drive fails within the RAID group.
dParity disk
Stores diagonal parity information that is used for data reconstruction when two disk drives fail within the RAID group, if RAID-DP is enabled.