Re: Arguments Pro/Contra Software Raid

Steve Atkins <steve(at)blighty(dot)com> writes:

> On May 9, 2006, at 2:16 AM, Hannes Dorbath wrote:
>
> > Hi,
> >
> > I've just had some discussion with colleagues regarding the usage of
> > hardware or software raid 1/10 for our linux based database servers.
> >
> > I myself can't see much reason to spend $500 on high end controller cards
> > for a simple Raid 1.
> >
> > Any arguments pro or contra would be desirable.

Really most of what's said about software raid vs hardware raid online is just
FUD. Unless you're running BIG servers with so many drives that the raid
controllers are the only feasible way to connect them up anyways, the actual
performance difference will likely be negligible.

The only two things that actually make me pause about software RAID in heavy
production use are:

1) Battery backed cache. That's a huge win for the WAL drives on Postgres.
'nuff said.

2) Not all commodity controllers or IDE drivers can handle failing drives
gracefully. While the software raid might guarantee that you don't actually
lose data, you still might have the machine wedge because of IDE errors on
the bad drive. So as far as runtime, instead of added reliability all
you've really added is another point of failure. On the data integrity
front you'll still be better off.

--
Greg