Re: Raid 1 vs Raid 5 for tablespaces

Tim,

Are you suggesting that HW RAID 1 with SW RAID 0 is a better combination than HW RAID 1 and HW RAID 0?

If so, why?

Jared

On Tue, 2003-08-12 at 21:59, Tim Gorman wrote:
> Software RAID-1 can mirror across controllers, channels, and storage arrays,
> should any of those be considered a single-point-of-failure...
>
> The combination of HW RAID-1 and SW RAID-0 is optimal for performance, if
> the HW supports it...
>
>
> on 8/12/03 9:04 PM, Matthew Zito at mzito_at_gridapp.com wrote:
>
> >
> > Actually, as of AIX 4.3.3, it does support 0+1 for LVs, but that wasn't the
> > scenario I was imagining. I was envisioning creating a set of RAID-1 raid
> > groups on the storage array and then striping across them using the LVM.
> > RAID-1 is one of those things that I feel is generally better to let your
> > storage array handle - software RAID-1 requires your host to generate double
> > the I/Os and should one side of the pair fail, hardware arrays tend to
> > recover more gracefully than software raid. RAID-0, by comparison, is very
> > easy.
> >
> > Thanks,
> > Matt
> >
> >
> > ----- Original Message -----
> > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > Sent: Tuesday, August 12, 2003 9:44 PM
> >
> >
> >> The AIX LVM supports RAID-0 and RAID-1, but not together, as you state.
> >>
> >> However, a rude form of RAID-0 can be achieved by specifying "max
> > allocation
> >> policy", which will cause round-robin distribution of physical extents
> > (PEs)
> >> across a list of physical volumes (PVs), thereby approximately RAID-0 at a
> >> large granularity (i.e. 4M, 8M, 16M per "stripe"). Still, it beats the
> > heck
> >> out of RAID5...
> >>
> >>
> >> on 8/12/03 12:24 PM, Schauss, Peter at peter.schauss_at_ngc.com wrote:
> >>
> >>> Our hardware people tell me that our disk array will not support Raid
> > 10.
> >>> Given a choice between Raid 1 or 5 for my tablespaces, which one
> >>> is best? This is Oracle 8.1.7 on AIX 4.3.3. The application will
> >>> have a mix of read and write activity.
> >>>
> >>> Thanks,
> >>> Peter Schauss
> >>
> >> --
> >> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> >> --
> >> Author: Tim Gorman
> >> INET: tim_at_sagelogix.com
> >>
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Tim Gorman
> INET: tim_at_sagelogix.com
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jared Still
  INET: jkstill_at_cybcon.com

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