[LAU] RAID and AVLinux

[Fons Adriaensen]

On Mon, Oct 12, 2009 at 10:14:27PM +0200, Florian Faber wrote:

> > the failure of each individual disk is a statistically independent
> > event. there is absolutely no synchronized self-destruct of disks
> > belonging to the same batch.
> 
> It is not independent because the environment has an impact on the
> failure rate (vibration, delta temperature etc.). So it is more likely
> that another drive fails if one has already failed.

More likely is not the same as failure times clustering.

The latter will happen only in extreme cases, e.g. if your
server catches fire, or all disks get the same wrong power
voltages, etc. In such cases *all* disks will fail within
a short time, and there's little you can do about it.

In normal circumstances failure times are independent
random variables, even if their expected values are
scaled by the same ratio.


Ciao,

-- 
FA

Io lo dico sempre: l'Italia è troppo stretta e lunga.