Chapter 10. Data protection with RAID Double Parity 163RAID-DP volume managementFrom a management and operational perspective, RAID-DP aggregates and traditionalvolumes work exactly as their RAID4 counterparts. The same practices and guidelines workfor RAID4 and RAID-DP. Therefore, little to no changes are required for standard operationalprocedures that are used by IBM System Storage N series administrators. The commandsthat you use for management activities on the storage controller are the same regardless ofthe mix of RAID4 and RAID-DP aggregates or traditional volumes. For instance, to addcapacity, run the [aggr | vol] add name X command as you do for a RAID4-based storage.10.5 Hot spare disksA hot spare disk is a storage system disk that is not assigned to a RAID group. It does not yethold data, but is ready for use. In a disk failure within a RAID group, Data ONTAPautomatically assigns hot spare disks to RAID groups to replace the failed disks.Hot spare disks do not have to be in the same disk shelf as other disks of a RAID group to beavailable to a RAID group, as shown in Figure 10-27.Figure 10-27 RAID-DP protectionTip: You need at least one spare disk available per aggregate, but no more than three. Inaddition, the available spares need at least one disk for each disk size and disk type that isinstalled in your storage system. This configuration allows the storage system to use a diskof the same size and type as a failed disk when you are reconstructing a failed disk. If adisk fails and a hot spare disk of the same size is unavailable, the storage system uses aspare disk of the next available size up.
