RAID arrays appear to the operating system (OS) as a single logical hard disk.
RAID employs the techniques of disk mirroring or disk striping.
While the levels of RAID listed in the 1988 report essentially put names to technologies that were already in use, creating common terminology for the concept helped stimulate the data storage market to develop more RAID array products.
According to Katz, the term inexpensive in the acronym was soon replaced with independent by industry vendors due to the implications of low costs.
The number of levels has since expanded and has been broken into three categories: standard, nested and nonstandard RAID levels.
RAID 1: Also known as disk mirroring, this configuration consists of at least two drives that duplicate the storage of data. Read performance is improved since either disk can be read at the same time.
When in the form of a Peripheral Component Interconnect or PCI Express card, the controller can be designed to support drive formats such as SATA and SCSI.
A firmware-based RAID controller chip is located on the motherboard, and all operations are performed by the CPU, similar to software-based RAID.In a multiuser system, better performance requires that you establish a stripe wide enough to hold the typical or maximum size record. Disk mirroring and disk striping can be combined on a RAID array.Mirroring and striping are used together in RAID 01 and RAID 10.Mirroring copies identical data onto more than one drive.Striping partitions each drive's storage space into units ranging from a sector (512 bytes) up to several megabytes.However, with firmware, the RAID system is only implemented at the beginning of the boot process.