Raid Levels - Samsung 840 White Paper

Enhancing SATA Performance with RAID
Today's SSDs are maximizing the performance potential of the current SATA 3.0 interface generation. One way to
increase performance beyond standard single drive SATA configurations is to pair 2 or more drives together using SATA's
native RAID support.
RAID, which stands for Redundant Array of Independent/Inexpensive Disks, is a type of storage system in which a number
of drives (at least 2) are combined into one logical unit. RAID is used to improve performance, improve reliability, or some
combination of these two. Data can be distributed among the drives in a RAID array in one of several ways (called RAID
levels). The most common RAID levels are RAID 0 and RAID 1. With the introduction of its 7 Series Chipsets and the latest
Intel Rapid Storage Technology (IRST) drivers (11.0 or later), Intel is now fully supporting SSD technology, including the
TRIM maintenance command, in RAID 0 arrays. In the past, the lack of TRIM for RAID 0 was a source of frustration, as the
performance improvements initially gained through the RAID array were mitigated by the performance deficits caused
by the lack of TRIM. Thus, with the addition of TRIM support for RAID 0, it is useful to understand RAID technology and
who (and why) an individual might choose to use it.

RAID Levels

RAID 0
RAID 0, which requires a minimum of two drives and whose primary purpose is speed, divides files into chunks, or stripes,
which are split among the available drives and written in parallel. By doing this, it is also possible to read smaller sections
of the original file in parallel. This parallelism is what allows for the drastic performance improvements that RAID 0 offers.
If one drive fails, however, all data (having been broken into chunks) is destroyed; and the likelihood of failure increases as
more drives are added to the array.
RAID 1
RAID 1, which also requires a minimum of two drives, writes data identically to multiple drives and offers performance
Parallelism improves performance
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