[brianwski]

I don't think the math works. I posted this above:

I think the calculation is replacing one drive takes about 15 minutes of work. If we have 30,000 drives and 2 percent fail, it takes 150 hours to replace those. In other words, one employee for one month of 8 hour days. Getting the failure rate down to 1 percent means you save 2 weeks of employee salary - maybe $5,000 total? The 30,000 drives costs you $4 million, so who cares about $5k here or there?

The $5k/$4million means the Hitachis are worth 1/10th of 1 percent higher cost to us. ACTUALLY we pay even more than that for them, but not more than a few dollars per drive (maybe 2 or 3 percent more).

Moral of the story: design for failure and buy the cheapest components you can. :-)

[olov]

Ok, after converting to MTBF the numbers make more sense: An AFR of 0.9% means a MTBF of 968947 hours (111 years). An AFR of 3.2% means a MTBF of 269346 hours (31 years).

I guess an MTBF of 31 years is plenty for your needs. Thanks again for sharing the data.

[im3w1l]

I think the failure rate will go up in old age. I just don't see those drives still working in 100 years.