Originally Posted by assassin
Like I said before isn't there just as good a chance (better actually since the failure rates of hard drives are relatively low) that you would actually be better off to grab drives from a single batch?
But that's the point, if you buy all your drives from the same batch, then you'll get a set of drives with similar failure characteristics
. Theoretically you're better off if the drives your array have different failure characteristics
. If you get ten drives from the same batch, and one fails
, then the odds are higher that another drive will fail at the same time (or while the rebuild is going on) than if you'd bought ten drives from ten different batches.
I don't see how grabbing 10 drives from 10 batches necessarily protects you at all.
It protects you because drives from different batches will have been through different manufacturing/transportation history and are more likely to have different failure characteristics
, such that you are less likely to have two drives fail at the same time thus killing your array and all your data. Take for example if there's some manufacturing defect that goes undetected, if you bought all your drives from the same batch with the same defect odds are high more than one of those drives will fail at the same time and kill the array and everything on it. Where as if you bought the drives from different batches, your odds are much better that they don't all have the same defect and that not more than one will fail from it.
And unless you have 1000 drives I am not sure it makes any sense.
All that said, I agree, I don't think it's really worth a lot of consternation. IMO it's more trouble to try and buy drives from different batches for the small decrease in likelihood that multiple drives will fail in the array before you can replace/rebuild.