Monday, October 10, 2016
How RAID 5 work Shorter and easier to interpret than ever!
How RAID 5 work Shorter and easier to interpret than ever!
How RAID 5 work? Shorter and easier to interpret than ever!
We all have to lack of time to study the long and complex information about RAID theories, but you
may be interested in how RAID 5 works. We made it easy for you by providing explain shorter and
easier than ever before.
RAID 5 - How does it work?
First we need to remind you of the definition of XOR:
XOR result of the function is equal to 1 if all the arguments are different.
XOR (0, 1) = 1
XOR (1, 0) = 1
XOR output function is equal to 0 if all the arguments are the same.
XOR (0, 0) = 0
XOR (1, 1) = 0
Now lets assume we have 3 drives with the following bits:
| 101 | 010 | 011 |
I daresay XOR that data and put it on the CD 4
XOR (101, 010, 011) = 100 (XOR (101010) = 111, and XOR (111, 011) = 100
Therefore, the data on the four engines looks like this below:
| 101 | 010 | 011 | 100 |
Now lets see how it works XOR MAGIC. Lets assume the second drive failed. When we calculate
XOR all the remaining data will be present from the engine missing.
| 101 | 010 | 011 | 100 |
XOR (101, 011, 100) = 010
You can check the other drives were missing, and will XOR of the remaining data always give you
exactly the data from your missing disk.
| 101 | 010 | 011 | 100 |
XOR (101, 010, 100) = 011
What works for 3-bit and 4 drives only, and works for any number of parts and any number of drives.
RAID 5 real has the most common form of 64K stripe size (65536 * 8 = 524288 bit)
Thus, the real XOR engine only needs to deal with the 524288-bit 3-bit and not, as in our practice.
This is the reason that RAID 5 needs to be very effective XOR engine in order to calculate it quickly.
Even when you add one drive for parity will be able to re-build the lost data in the event of a drive failure.
In our example we have explained RAID 4, where a dedicated parity drive. RAID 5 will parities
distributed evenly among all the drives. Provides parity distributed a slight increase in performance,
but the magic XOR is the same.
To learn more about RAID 5 please go to the Wikipedia article.
Go to link download
alternative link download
