HP 3PAR StoreServ 7400 2-node HP 3PAR StoreServ Storage Concepts Guide (OS 3.1 - Page 35

RAID Types, RAID 0, RAID 1 and 10, RAID Multi-parity MP

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failures. When the destination logical disks become available again, the system automatically writes the preserved data from the preserved data logical disks to the destination logical disks. • Administration volume logical disks provide storage space for the admin volume, a single volume created on each system during installation. The admin volume is used to store system administrative data such as the system event log. RAID Types The 3PAR storage system supports the following RAID types: • RAID 0 • RAID 10 (RAID 1) • RAID 50 (RAID 5) • RAID Multi-parity (MP) RAID 0 On a RAID 0 logical disk, data is striped across rows of chunklets on different physical disks. The number of chunklets in a RAID 0 set is known as the set size, which is always 1 for a RAID 0 logical disk. The number of sets in a row is known as the row size. The system accesses data from a RAID 0 logical disk in step sizes, where the step size is the number of contiguous bytes that the system accesses before moving on to the next chunklet. A RAID 0 logical disk improves performance but provides no fault-tolerance. Figure 3 (page 35) shows a RAID 0 logical disk with a set size of 1 and a row size of 3: Figure 3 Data Striped Across Chunklets on a RAID 0 Logical Disk RAID 1 and 10 On a RAID 10 logical disk, 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 may be located in different drive magazines or even different drive cages. The number of chunklets in a RAID 1 set is the set size (or mirror depth). The number of sets in each row is the row size. The maximum row size is 40. The system accesses data from a RAID 10 logical disk in step sizes. A step size is the number of contiguous bytes that the system accesses before moving on to the next chunklet. A RAID 1 set can function with the loss of all but one of the chunklets in the set. Figure 4 (page 36) shows a RAID 10 logical disk with a set size of 2 and a row size of 3 in two rows: RAID Types 35

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failures. When the destination logical disks become available again, the system automatically
writes the preserved data from the preserved data logical disks to the destination logical disks.
•
Administration volume
logical disks provide storage space for the
admin volume
, a single
volume created on each system during installation. The admin volume is used to store system
administrative data such as the system event log.
RAID Types
The 3PAR storage system supports the following RAID types:
•
RAID 0
•
RAID 10 (RAID 1)
•
RAID 50 (RAID 5)
•
RAID Multi-parity (MP)
RAID 0
On a RAID 0 logical disk, data is striped across rows of chunklets on different physical disks. The
number of chunklets in a RAID 0 set is known as the
set size
, which is always 1 for a RAID 0 logical
disk. The number of sets in a row is known as the
row size
. The system accesses data from a RAID
0 logical disk in
step sizes
, where the step size is the number of contiguous bytes that the system
accesses before moving on to the next chunklet. A RAID 0 logical disk improves performance but
provides no fault-tolerance.
Figure 3 (page 35)
shows a RAID 0 logical disk with a set size of 1 and a row size of 3:
Figure 3 Data Striped Across Chunklets on a RAID 0 Logical Disk
RAID 1 and 10
On a RAID 10 logical disk, 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 may be located in different drive magazines or even different
drive cages. The number of chunklets in a RAID 1 set is the
set size
(or
mirror depth
). The number
of sets in each row is the
row size
. The maximum row size is 40. The system accesses data from
a RAID 10 logical disk in
step sizes
. A step size is the number of contiguous bytes that the system
accesses before moving on to the next chunklet. A RAID 1 set can function with the loss of all but
one of the chunklets in the set.
Figure 4 (page 36)
shows a RAID 10 logical disk with a set size of 2 and a row size of 3 in two
rows:
RAID Types
35