I wrote this up on the bus going home last night. Tell me what you think of
it. I know I am useing ideas that I got from other sources and that it
isn't really MY idea, but I wrote it and it makes sense to me so far, and I
wish I could implement it.
An Error Correcting File System with Even Parity
1 Byte = 8 Bits
Data Packet = 1 for the first bit
Error Correction Packet = 0 for first bit
Last bit is Parity bit
Parity is determined by the Data, or BYTE, contained in the packet, not
includeing the Packet Type Identifier. An Odd number of 1s in the Byte
would make the Parity bit a 1. An Even number of 1s makes the Parity bit a
0.
DP1 DP2
-------------- --------------
|1|10101100|0| |1|11101100|1|
-------------- --------------
-------------- --------------
|0|11001110|1| |0|11001010|0|
-------------- --------------
EP1 EP2
EP1 = Second half of DP1 and First half of DP2
EPx = Second half of DPx and First half of DP1
x=Last Packet
If one bit is missing, Parity can be used to restore it.
If one Packet is missing or damaged two other packets can be used to Rebuild
it.
If two bits in one Packet are lost, the Packet is lost.
If a DP and it's corisponding EP are lost, they can't be Rebuilt.
If the first bit of a packet is lost, one can look for it's corisponding
packet, whether DP or EP and set the identification bit.
If the Parity bit is lost, the data can be used to set it again.
I wrote this in such a way that the average person can hopefully grasp what
it is that I am talking about. I hope the verboseness and obviousness of it
doesn't insult you. It wasn't intended for the high tech experts. :)
I think this method of error correction could work really well as part of a
real file system, such as FAT16 or something, but since it takes up more
than twice the same amount of space as it normaly would, it would be a bad
idea to protect ALL of your files with this scheme. I would only use it on
the most important files. Also, I would have backup copies of important
files being stored elswhere on the drive, on the fly, so that if even this
error correction scheme is unable to protect the file, it will have a backup
available to automaticaly replace the file.
I would also be useing some kind of External backup method for my important
files and would keep at least two copies of every backup, and keep one of
those two copies Off Site, somewhere else.
This way it would be nearly impossible to lose my most important files. :)
And I wouldn't have to try to use RAID. :)
Hope it makes sense to you guys, and I really hope it is either
implementable on my home machine, for free, or isn't required because of
something better that is also free. :)
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