On Sat, Jul 15, 2023 at 06:17:57PM +0100, Simon wrote:
> Hendrik Boom <hendrik@???> wrote:
>
> >> Indeed, but guess what you get when you buy any storage appliance !
> >> The last drives I bought were used 6TB ones - apart from the cost, I figured they’d be “run in”.
> >
> > I don't know what you mean by this.
> > I haven't been able to guess and what is “run in”?
>
> Buy any new storage appliance, and you’ll get new drives, all the same model, and almost certainly from the same manufacturing batch - so plenty of scope for common mode failures that could cause multiple drive failures in a short space of time. As mentioned, ideally you want drives from different batches to avoid this issue. With my work hat on, we deal with safety critical systems where we have massive redundancy - but a big concern is common cause failures that could affect multiple nodes and thus render the redundancy moot.
>
> “Run in” comes from the automotive world. Going back, not too far, it was normal practice to “run in” a new (or newly overhauled) engine - avoiding prolonged runs at high speed and/or high power until the piston rings and bores had had change to wear to fit each other. Not running in a new engine could significantly reduce it’s life till it next needed an overhaul by not allowing the machining in the bores to wear down correctly, which can significantly affect the oil retaining properties, hence lubrication, and hence future wear of piston rings and bores.
>
> The last drives I bought were used (presumably from some large bit barn having a periodic hardware refresh, so I figure could be from different batches (I bought them some time apart, and they had significantly different power on hours), and would be well past any early mortality phase (like many products, they tend to follow the classic bathtub curve https://en.wikipedia.org/wiki/Bathtub_curve).

Thank you. A very clear explanation.

-- hendrik