Re: Postgresql on software RAID

Patrick Spinler wrote:
> Adam Witney wrote:
> > Hi all,
> >
> > I am experimenting with a few OS's for my new hardware. I plan to have a
> > software RAID5 device for my pgsql data directory.
> >
> > I have been experimenting with FreeBSD and with Linux, does anyone have any
> > thoughts on whether vinum RAID devices are better than Linux software RAID?
> > Or vice versa... Or no difference at all? Any gotchas I should bear in mind?
> >
>
> Of interest, there are a number of "old school" dba's of my aquantance
> who swear vociferously whenever the words RAID 5 and Database are
> mentioned in association with each other.
>
> 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.
>
> I've never had a chance to benchmark a comparison between the two and
> draw my own conclusions, but it might be interesting to do so.

I have heard you need +6 disks for RAID5 to be faster than Raid 0+1.

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