2010/12/18 Gael Le Mignot <gael(at)pilotsystems(dot)net>:
> Hello Scott!
> Fri, 17 Dec 2010 19:06:15 -0700, you wrote:
> > On Fri, Dec 17, 2010 at 10:32 AM, Craig James
> > <craig_james(at)emolecules(dot)com> wrote:
> >> RAID5 is a Really Bad Idea for any database. It is S...L...O...W. It does
> >> NOT give better redundancy and security; RAID 10 with a battery-backed RAID
> >> controller card is massively better for performance and just as good for
> >> redundancy and security.
> > The real performance problem with RAID 5 won't show up until a drive
> > dies and it starts rebuilding
> I don't agree with that. RAID5 is very slow for random writes, since
> it needs to :
Trust me I'm well aware of how bad RAID 5 is for write performance.
But as bad as that is, when the array is degraded it's 100 times
worse. For a lot of workloads, the meh-grade performance of a working
RAID-5 is ok. "Not a lot of write" data warehousing often runs just
fine on RAID-5. Until the array degrades. Then it's much much slower
than even a single drive would be.
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