The multitudes of RAID 5 setups are not isolated in the world of Enterprise Servers, home and small business users use them as well. This fact has brought an interesting quandary to the RAID 5 data recovery specialist.
RAID 5, is without a doubt one of, if not the single most difficult recovery procedures in the industry. Along with that difficulty comes a very hefty price tag ranging from as little as $2500.00 to as much as $7500.00 for a three drive RAID 5 data recovery. The pricing range is based on drive size, operating system type, extent of damage, virtualization such as VMWare, and finally time allocated to recover the RAID. The small business, and or home user normally does not have that kind of ready cash to recover the RAID, but, the data to them may be just as important to them as any high end five star enterprise business. There are times when a ‘Do It Yourself’ solution can defray a great deal of the cost and ultimately allow a recovery for pennies on the dollar.
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.