Re: DASD Disk Layout Advice

From: joel garry <>
Date: Fri, 11 Dec 2009 09:18:18 -0800 (PST)
Message-ID: <>

On Dec 10, 12:02 pm, Frank van Bortel <> wrote:
> joel garry wrote:
> > On Nov 27, 7:45 am, Pat <> wrote:
> >> 3) RAID 5 ... with todays' controllers is that getting used more
> >> often? It was drilled into my head years ago that you don't put OLTP
> >> data on RAID 5, but then it was drilled into my head that you never
> >> mount your tablespace over NFS too and that changed :)
> > I'm a BAARFer by nature, but I have to admit, as long as it isn't in
> > degraded mode and nobody does anything stupid like yanking out two
> > drives and you aren't near saturating volumes of data movement, it
> > actually works pretty well on at least the specific configuration we
> > have, which is quite different than yours.  Just get management to at
> > least agree to go away from it if some actual evidence of severe
> > performance degradation occurs.  I see it during mass app upgrades,
> > which do things like add columns to every row in the largest tables,
> > but that just is a matter of waiting until things are done.
> > Performance issues during normal ops seem to skew towards cpu issues,
> > for my configuration.  Generally they are due to DSS type operations
> > on my OLTP system.  Which are decided upon by management, so are easy
> > to turn around into "hardware enhancement requirements."
> > jg
> > --
> > is bogus.
> >
> Dear BAARF member # 127 (or should I say "0xFF"). One thing is still
> forgotten: any disk failure on a degraded RAID-5 will make your data
> go POOF!
> Stop worrying, go SAME (Stripe And Mirror Everything, or RAID 0+1)
> --
> Regards,
> Frank van Bortel (BAARF #287)

LOL! I asked them specifically for that number, 'cause it's so k001.

Actually, it's potentially worse than POOF!

I wasn't clear in distinguishing performance degradation from degraded mode. I meant, be sure and get some management sign-off on switching to a better raid layout if normal ops run into I/O bottlenecks. In addition to that, CYA for degraded mode+disk failure.

The next hot thing is snapping file changes instead of just using standby. Sigh.


-- is bogus.
Received on Fri Dec 11 2009 - 11:18:18 CST

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