Re: which dual-CPU hardware/OS is fastest for PostgreSQL?

Greg Stark wrote:
> Jan Dittmer <j(dot)dittmer(at)portrix(dot)net> writes:
>
>
>>You could always do raid 1 over raid 0, with newer kernels (2.6ish)
>>there is even a dedicated raid10 driver.
>
>
> Aren't you much better off doing raid 0 over raid 1?
>
> With raid 1 over raid 0 you're mirroring two stripe sets. That means if any
> drive from the first stripe set goes you lose the whole side of the mirror. If
> any drive of the second stripe set goes you lost your array. Even if they're
> not the same position in the array.
>
> If you do raid 0 over raid 1 then you're striping a series of mirrored drives.
> So if any drive fails you only lose that drive from the stripe set. If another
> drive fails then you're ok as long as it isn't the specific drive that was
> paired with the first failed drive.

Ever heart of Murphy? :-) But of course you're right - I tend to mix up
the raid levels...

Jan