E-3
About RAID
RAID 1 offers no write performance advantage over a simple
volume configuration. However, because the drives share read load
equally, RAID 1 provides improved read performance. An example
of a RAID 1 array is shown below.
RAID 5
This RAID type requires at least three drives. Like RAID 0, data is
striped across the drives. The controller generates parity every time
data is written to the array, which is distributed in stripes across all
the drives. The total parity occupies the equivalent of one drive.
In the event of a drive failure, the contents of the failed drive can be
rebuilt from the data and parity on the remaining drives.
RAID 1
Data 0
Drive
Drive
Data 1
Data 2
Data 3
Data 0
Data 1
Data 2
Data 3
RAID 5
Data 3
Data 0
Parity 3
Data 6
Data 4
Data 1
Data 9
Parity 2
Parity 1
Data 2
Data 10
Data 7
Parity 0
Data 5
Data 11
Data 8
Drive
Drive
Drive
Drive
