Raid; Raid Types - HP 3PAR StoreServ 7200 2-node Manual

13 RAID

RAID (redundant array of independent disks) is a storage functionality that distributes data in units
called chunklets across physical disks in order to create redundancy and therefore increase the
stability of your stored data. On the HP 3PAR StoreServ 7000 Storage system, a chunklet is 1 GiB.
RAID is one of the parameters of a CPG (common provisioning group), the storage pool from which
volumes allocate storage space. You can set the RAID type, along with other parameters, when
you create a CPG, and you can also modify an existing CPG's RAID.

RAID Types

HP 3PAR storage systems support the following types of RAID:
RAID 0: Data is striped across rows of chunklets on different physical disks.
RAID 0 improves performance but provides no fault-tolerance.
RAID 10 (RAID 1): Data is striped across RAID 1 (or mirrored) sets. A RAID 1 set is made up
of two or more chunklets that contain the same data. The chunklets in each set are distributed
across different physical disks, which could be located in different drive magazines or different
drive cages.
A RAID 1 set can function with the loss of all but one of the chunklets in the set.
RAID 50 (RAID 5): Data is striped across rows of RAID 5 sets. A RAID 5 set, or
made up of at least three chunklets. Each RAID 5 set contains a total of two chunklets of space
for data and one chunklet of space for parity. The chunklets in each RAID 5 set are distributed
across different physical disks, which could be located in different drive magazines or different
drive cages.
A RAID 5 set can function with the loss of any one of the chunklets in the set.
RAID Multi-parity (MP) (RAID 6): Data is striped across rows of RAID MP sets. A RAID MP set,
or double-parity set, is made up of at least 8 chunklets. Each RAID MP set contains a total of
6 chunklets of space for data and 2 chunklets of space for parity. The chunklets in each RAID
MP set are distributed across different physical disks, which could be located in different drive
magazines or different drive cages.
A RAID MP set can function with the loss of any two of the chunklets in the set.
For more detail on the implementation of RAID in HP 3PAR storage systems, see the HP 3PAR
StoreServ Storage Concepts Guide. To access this document, go to the HP 3PAR StoreServ Storage
site and click the Support link for your product:
http://www.hp.com/go/3par
parity set, is
RAID Types 47