What is RAID?
RAID (redundant array of independent disks; originally redundant array of inexpensive disks) is a way of storing the same data in different places (thus, redundantly) on multiple hard disks. By placing data on multiple disks, I/O (input/output) operations can overlap in a balanced way, improving performance. Since multiple disks increases the mean time between failures (MTBF), storing data redundantly also increases fault tolerance. Ask your RAID questions at ITKnowledgeExchange.com A RAID appears to the operating system to be a single logical hard disk. RAID employs the technique of disk striping, which involves partitioning each drive’s storage space into units ranging from a sector (512 bytes) up to several megabytes. The stripes of all the disks are interleaved and addressed in order.
Ans: RAID stands for Redundant Array of Inexpensive Disks. RAID uses multiple disks to increase performance and/or reliability. Many motherboards today support RAID in the forms of RAID0, RAID1 and RAID0+1. There exist other modes including RAID3 and RAID5. Advantages of RAID include – improved performance and/or reliability Disadvantages of RAID include – cost- multiple disks are treated as one array (2 60 gig drives for example will be treated as 1 60 gig array in a RAID configuration), reliability in RAID0 mode, efficiency- striped mode does not equate to a 100% performance boost. There is a certain overhead to RAID. RAID0 In a RAID 0 configuration, multiple disks are used to stripe data. Striping means spreading out the data over multiple drives. Since we are writing to multiple disks we are not bound by the performance limitation of a single disk resulting in greater performance since we can a) write to multiple disks simultaneously and b) read from multiple disks simultaneously.
What is RAID? Using Multiple Hard Drives for Performance and Reliability Introduction Back in the late 1980’s and early 1990’s, computer information servers were encountering a dramatic increase in the amount of data they needed to serve and store. Storage technologies were getting very expensive to place a large number of high capacity hard drives in the servers. A solution was needed and thus RAID was born. So what exactly is RAID? First of all, the acronym stands for Redundant Array of Inexpensive Disks. It was a system developed whereby a large number of low cost hard drives could be linked together to form a single large capacity storage device that offered superior performance, storage capacity and reliability over older storage solutions. It has been widely used and deployed method for storage in the enterprise and server markets, but over the past 5 years has become much more common in end user systems.
RAID stands for Redundant Array of Independent Disks and it basically involves combining two or more drives together to improve the performance and the fault tolerance. Combining two or more drives together also offers improved reliability and larger data volume sizes. A RAID distributes the data across several disks and the operating system considers this array as a single disk.
• RAID Levels – How the drives are organized • How to determine your RAID level • RAID 0 – Disk Striping • RAID 1 – Disk Mirroring • RAID 4 – Disk Striping with Parity on a Dedicated Drive • RAID 5 – Disk Striping with Distributed Parity • RAID 10 – Combination of RAID 0 & RAID 1 RAID (Redundant Array of Independent Disks) refers to multiple independent hard drives (the yellow pots in the picture) combined to form one large logical array (dashed pot). Data is stored on this array of disks with additional redundancy information. The redundancy information may be either the data itself (mirroring), or parity information calculated out of several data blocks (RAID 4, or RAID 5). With RAID in place, the operating system (Windows*, NetWare*, or Unix) no longer deals with individual drives, but instead with the entire disk array as one logical drive. The major objectives of RAID are to improve data availability and security.
