> > i think the lesson here is don't by cheep drives; if you > > have enterprise drives at 1e-15 error rate, the fail rate > > will be 0.8%. of course if you don't have a raid, the fail > > rate is 100%. > > > > if that's not acceptable, then use raid 6. > > Hopefully Raid 6 or zfs's raidz2 works well enough with cheap > drives!
don't hope. do the calculations. or simulate it. this is a pain in the neck as it's a function of ber, mtbf, rebuild window and number of drives. i found that not having a hot spare can increase your chances of a double failure by an order of magnitude. the birthday paradox never ceases to amaze. - erik
