Effects Of Bit Rot (Part II)
This is the hex1 dump of the original bitmap. You can recreate the file from the previous example by using a hex editor and enter these values:
Here is the hex dump of the corrupted bitmap, almost identical, except for one small difference.
Can you find it?
The difference between the two files is at position 0x000000C8. Look at the row labelled 000000C0, and then count 8 columns from the left. The original file has a value of 0xFF, while the corrupted file has a value of 0x7F.
|Original Representation||Original Value||Corrupted Representation||Corrupted Value|
|0111 1111||127 (7F)|
So the two files are identical in almost every way except for that single bit. A single bit flip caused that yellow spot you saw in the previous page. Over time as more bit rot creeps in the picture will change, and because the rotting is unpredictable and random, it is really hard to say for certain what the result will be.
- Hexadecimal is another way of representing numbers. Binary is base 2 (0, 1, 10, 11, 100, 101, …) , decimal system is base 10 (0, 1, …, 10, 11, 12, ….), and hexadecimal is base 16 (0, …, 9, a, b, …, e, f, 10, 11, 19, 1A, …)
Comment from: Frank Collins Visitor
I don’t believe bit rot is a problem and the Red Book standard copes with missing bits, to a point.
I store all of my music (FLAC, level 8 compression) on a NAS, using FreeNAS. It does a four-weekly scrub which detects and corrects bit rot on the whole file system. While bit rot isn’t a problem for me, it never will be.
It does a four-weekly scrub which detects and corrects bit rot on the whole file system. While bit rot isn’t a problem for me, it never will be.+1. FreeNAS for the win.
A "single-event upset" was also blamed for an electronic voting error in Schaerbeekm, Belgium, back in 2003. A bit flip in the electronic voting machine added 4,096 extra votes to one candidate. The issue was noticed only because the machine gave the candidate more votes than were possible. "This is a really big problem, but it is mostly invisible to the public," said Bharat Bhuva. Bhuva is a member of Vanderbilt University’s Radiation Effects Research Group, established in 1987 to study the effects of radiation on electronic systems.
Here is an interesting YouTube video about bit flipping.