Re: Postgresql on software RAID

On Tue, 16 Dec 2003, Robert Creager wrote:

> When grilled further on (Tue, 16 Dec 2003 22:30:04 -0600),
> Patrick Spinler <spinler@kmtel.com> confessed:
>
> >
> > According to the theory they expound, a database with any significant
> > write activity whatsoever should never be on raid 5, but instead be on
> > raid 0+1.
> >
>
> Kind of related and a point of reference.  We use ClearCase and have many
> multiple Gb vob's(databases). We were using RAID-5, but had to back off to RAID
> 0+1 because of performance reasons (which was indicated in the manual, once you
> read it...). This would happen around 1-2Gb's vob size.  Our usage of CC
> provides heavy writing activity to the underlying dB.
>
> I don't know what kind of dB engine Atria->Rational->IBM has implemented
> underneath, or even it it would look like a dB to someone who knew the
> difference...

Just wondering, was that on hardware or software RAID5, and if hardware
did it have battery backed cache controllers?  Makes a huge difference.  I
would never use SW RAID5 for heavily written databases.