Building a box
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Mike Dimmick wrote:
RAID 0 is highly unsafe - the failure rate of the array is the failure rate of each drive multiplied together (e.g. a 3% chance of failure of each drive becomes a 9% chance for two drives, 27% for three drives, 81% for four drives, and it's a good thing that 3% is a massive overestimate). It can be OK if you do RAID 10 which is a striped mirror - you have a redundant drive for each stripe, so it reduces the chances of losing the whole set.
Your math is wrong here. The proper calculation is that you have a 97% chance of non failure raised to the power of hte number of drives. 2 drives is .97^2 = 94.09% chance of nonfailure or ~6% of failure. 3 drives is 92.26, 4 88.53%. The easy way to demonstrate that your calculation is wrong is to look at 2 drives with a 10% failure rate. The odds of both failing isn't 10*10=100%.
You know, every time I tried to win a bar-bet about being able to count to 1000 using my fingers I always got punched out when I reached 4.... -- El Corazon
Yeah, I'm an idiot on that one. Percentages do tend to throw me sometimes. (The calculation of 'what should the excluding VAT price be if the including VAT price is X' is non-intuitive, it's X / 1.175 if your VAT rate is 17.5%.) Still, probability of failure of a RAID 0 array is greater than the probability of failure of each individual disk, and that's reason enough to take more care with the array than you would with a standalone disk.
DoEvents: Generating unexpected recursion since 1991