beautypg.com

Appendix, Appendix f, Understanding raid – DATOptic ARC-1680 Series User Manual

Page 176

background image

APPENDIX

176

Appendix F

Understanding RAID

RAID is an acronym for Redundant Array of Independent Disks. It

is an array of multiple independent hard disk drives that provides

high performance and fault tolerance. The SAS RAID control-

ler implements several levels of the Berkeley RAID technology.

An appropriate RAID level is selected when the volume sets are

defined or created. This decision should be based on the desired

disk capacity, data availability (fault tolerance or redundancy),

and disk performance. The following section discusses the RAID

levels supported by the SAS RAID controllers.

The SAS RAID controllers makes the RAID implementation and

the disks’ physical configuration transparent to the host operating

system. This means that the host operating system drivers and

software utilities are not affected, regardless of the RAID level

selected. Correct installation of the disk array and the control-

ler requires a proper understanding of RAID technology and the

concepts.

RAID 0

RAID 0, also referred to as striping, writes stripes of data across

multiple disk drives instead of just one disk drive. RAID 0 does

not provide any data redundancy, but does offer the best High-

speed data throughput. RAID 0 breaks up data into smaller blocks

and then writes a block to each drive in the array. Disk strip-

ing enhances performance because multiple drives are accessed

simultaneously; the reliability of RAID level 0 is less because the

entire array will fail if any one disk drive fails.