E-2
About RAID
Spanned Volume
A spanned volume is created by joining, or concatenating, two or
more drives. The drives do not have to be of equal capacity and are
connected end-to-end. A spanned volume offers no redundancy
and no performance advantage over a single drive.
RAID 0
A RAID 0 is created by striping data across two or more drives.
This striping scheme creates no redundancy to protect the data.
However, because the drives share load equally, RAID 0 provides
the best read and write performance of any RAID type.
An example of a RAID 0 array is shown below.
RAID 1
A RAID 1 array is created by copying, or mirroring, all data from
one drive onto a second drive. This mirroring provides redundancy,
ensuring that if one drive fails no data is lost. Redundancy also
means that only half of the total capacity is available.
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 above.
RAID 0
Data 0
Data 2
Data 4
Data 6
Data 1
Data 3
Data 5
Data 7
Drive Drive
RAID 1
Data 0
Drive Drive
Data 1
Data 2
Data 3
Data 0
Data 1
Data 2
Data 3