14-01-2011, 12:13 PM
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Submitted by:
Sandeep Kumar
Anirudh Kumar
Rakesh Ranjan
Shiv kuar singh
Submitted to:
Mr. Ajay Kaul
What is RAID???
RAID stands for “Redundant array of inexpensive disks” or “Redundant array of independent disks”.
Definition
RAID is a way of storing the same data in different places on multiple hard disks.
By placing data on multiple disks, I/O operations can be performed easily.
A RAID appears to the operating system to be a single logical hard disk.
Why RAID?
To mitigate the problem of MTBF.
To increase fault tolerance.
To increase performance of I/O.
To storage reliability through redundancy.
To increase capacity.
To provide higher availability in case of disk failure.
RAID components
Host
Array of disks.
RAID controller.
Array of disks:-
It contains two or more disks .
This looks like one very fast, very reliable, very large disk to the host computer.
Disks are enclosed in smaller enclosures.
RAID controller:-
RAID controller is an electronic device.
It provides the interface between the host computer and array of disks.
RAID controller makes the array of disks , which works as a logical disk for the operating system.
It overcomes the disk performance limitation by stripping the data across the array of disks.
It uses the parallel data paths for the I/O operations.
Data transfer rate is as high as 35 MBPS while only 10 MBPS in case of single disk.
It handles following tasks:
Management and control of disk aggregation.
Translation of I/O request between logical disks and physical disks.
Data regeneration if disk failure occurs.
RAID concepts
RAID uses three main concepts as following:
Mirroring:
where multiple disks contain identical data.
Ex- used in RAID level-1.
