RAID( Redundant array of

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RAID( Redundant array of Inexpensive Disk ) : 

RAID( Redundant array of Inexpensive Disk )

Slide 2: 

History It first defined by David A. Patterson, Garth A. Gibson, and Randy Katz at the University of California, Berkeley in 1987 to describe a redundant array of inexpensive disks. What is RAID - It is a technology that allowed computer users to achieve high levels of storage reliability from low-cost and RAID allows you to store the same data redundantly (in multiple paces) in a balanced any to improve overall performance. What is RAID

Why RAID? : 

Why RAID? Protect From MTBF Better Data Security and Fault Tolerance Improve Availability Improve Performance and Greater Capacity

Array : 

Array an array is a method for storing information on multiple devices.) In general, an array is a number of items arranged in some specified way

RAID IDEA : 

RAID IDEA Several improvements in disk-use techniques involve the use of multiple disks working cooperatively. Disk striping uses a group of disks as one storage unit. RAID schemes improve performance and improve the reliability of the storage system by storing redundant data. Mirroring or shadowing keeps duplicate of each disk. Block interleaved parity uses much less redundancy

RAID Common Characteristics : 

RAID Common Characteristics A set of physical disk drives viewed by the OS as a single logical drive. Data are distributed across the array of disk drives. Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure.

RAID Structure : 

RAID Structure RAID – provides reliability via redundancy. RAID is arranged into six different levels:

RAID 0 Striping : 

RAID 0 Striping

Slide 9: 

RAID0 is simply data striped over several disks. This gives a performance advantage, as it is possible to read parts of a file in parallel. However not only is there no data protection, it is actually less reliable than a single disk, as all the data is lost if a single disk in the array stripe fails. Stripe width refer to number of parallel stripe that can be read and write to the disk simultaneously. Stripe can performed in byte level or in blokes. In byte level striping first byte data can sent to first drive and second byte to the second drive and so on.

Slide 10: 

Advantages:- Increased storage performance No loss in data capacity Disadvantages:- No redundancy of data

RAID1 : 

RAID1 RAID1 is data mirroring. Two copies of the data are held on two physical disks, and the data is always identical. RAID1 has a performance advantage, as reads can come from either disk, and is simple to implement. However, it is expensive, as twice as many disks are needed to store the data. Fault Tolerance when one disk failure. Read any disk in Parallel.

Slide 12: 

Advantages: Provides full redundancy of data Disadvantages Storage capacity is only as large as the smallest drive No performance increases Some downtime to change active drive during a failure

Why RAID? : 

Why RAID?

Why RAID? : 

Why RAID?

Why RAID? : 

Why RAID?

Why RAID? : 

Why RAID?