Re: [Hampshire] Gentoo adaptec RAD controller hangs

>> RAID-5 is computationally expensive, and as it
>> relies on at least three drives as opposed to
>> RAID-1's two, it has a shorted MTBF.
>
> Really? Do you have a reference for that?
>
> I can see that RAID 5 is more vulnerable after a
> drive failure and before rebuild completes - in
> that state, two-drive RAID 1's MTBF will be that
> of the single working drive, whereas RAID 5's MTBF
> will be combination of the two or more working
> drives. That's assuming the rest of the system is
> identical.
>
> When operating in redundant mode, don't the two
> levels have the same MTBF - again, assuming
> otherwise identical systems?
>

System MTBF = component MTBF/n
where n is # of components.

So for a component with MTBF of 50k hrs a 2 disk (RAID-1) system has
an MTBF of 25k hours, and a 3 disk (RAID-5) system has an MTBF of
~16.7k hrs.

During rebuilts the above RAID-1 has an MTBF of 50 k hrs again, and
the above RAID-5 has 25k hour MTBF.