RAID-5 is very popular in todays server machines. I am just Elaborating the magic of this technology so to get the detail knowledge about disk failure rate, perforamance and data recovery techniques you can visit sites like wikipedia.org I'll try to go on simple and smooth way to make my thread understandable.
In raid-5 minimum 3 disks of same size and specification are used. I am using 3 disk scenario in my post. Fore example if we use 3 disks of 300GB our total disk space equals 900GB but in raid-5 we get 600GB for data and 300 GB for making RAID. Raid-5 uses XOR logical gate. We know that all data in computer is manipulated in binary so data bits are distributed over 2 disks and the result of XOR of first 2 disks is placed over 3rd disk.
see the following example.
Disk 1 Disk 2 Disk 3 [disk1 XOR disk2]
0110 0011 1001
now consider if disk one fails, we raplace it with a new one then RAID controler device automaticly takes XOR of Disk 2 and Disk 3 and result is re-built over Disk 1. Same procedure occur if any one disk fails. It's the magic of XOR that by taking the XOR of bits of any two disks we will get the bits of
3rd one. I encourage you to practice it over paper.
Thanks and ragards.
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