The following is a simple lesson in basic RAID 5 data recovery that can be employed by most end users who have a rudimentary understanding of how to install simple tools and basic XOR mathematics.
First and foremost, XOR math has been around much longer than RAID 5 technology. I was first introduced to it when I started programming on an old ATARI 400 using player missile graphics. Using XOR math allowed for a simple approach to animated icons in a game without using back end buffers and screen swaps. Through XOR math video memory was kept intact not by saving it to a back buffer but by performing high speed calculations on the data. A sort of embedded shadow of the original data.
XOR math is calculated by taking two values and performing a bit level XOR procedure, in order to get a third value. The following is an XOR truth chart to illustrate what happens to each iteration of bit wise XORing. The number ‘1’ is considered ‘T’rue, and the number ‘0’ is considered ‘F’alse.
- T XORed with T = F
- T XORed with F = T
- F XORed with T = T
- F XORed with F = F
How does this help us with recovering a RAID 5 that has NTFS as the primary file system? Part 2 will give more insight into how this simple XOR truth table unlocks the key to RAID 5 technology.
Reference: http://dtidatarecovery.com/practical-raid-5-data-recovery-and-xor-mathematics-in-ntfs-5-part-1/
