Data ONTAP classifies disks as one of four types for RAID: data, hot spare, parity, or dParity. The RAID disk type is determined by how RAID is using a disk; it is different from the Data ONTAP disk type.
- 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.