You can grow volumes though without putting the RAID under software control.
Veritas Volume Mgr allows you to do that.
Jared
| "Matthew Zito" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED] 08/13/2003 09:14 AM
|
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> cc: Subject: RE: Raid 1 vs Raid 5 for tablespaces |
The _only_ even theoretical advantage to software RAID-0 is that software
RAID implementations tend to have more flexibility than the hardware ones.
For example, there are a number of software RAID implementations that allow
you to grow RAID-0 volumes, something that is generally not allowed in
hardware RAID, and most of those allow you to do it online. Some of the
better software RAID implementations even allow for online volume type
conversion - from RAID-1 to RAID-5 when adding a third disk to a mirrored
pair, as a random example.
Beyond that, there's no reason to have software RAID. Any other extraneous
advantages can be gleaned by using a traditional VM on top of hardware
RAID-ed devices. And even some of that stuff is better in hardware. :)
Thanks,
Matt
--
Matthew Zito
GridApp Systems
Email: [EMAIL PROTECTED]
Cell: 646-220-3551
Phone: 212-358-8211 x 359
http://www.gridapp.com
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Jared Still
> Sent: Wednesday, August 13, 2003 11:54 AM
> To: Multiple recipients of list ORACLE-L
> Subject: 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 [EMAIL PROTECTED] 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" <[EMAIL PROTECTED]>
> > > 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
> [EMAIL PROTECTED] 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: [EMAIL PROTECTED]
> > >>
> > >> Fat City Network Services -- 858-538-5051
> http://www.fatcity.com
> > >> San Diego, California -- Mailing list and web
> hosting services
> > >>
> -------------------------------------------------------------------
> > >> --
> > >> To REMOVE yourself from this mailing list, send an E-Mail message
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> > >> also send the HELP command for other information (like
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> > >>
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Tim Gorman
> > INET: [EMAIL PROTECTED]
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web
> hosting services
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>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Jared Still
> INET: [EMAIL PROTECTED]
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
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--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Matthew Zito
INET: [EMAIL PROTECTED]
Fat City Network Services -- 858-538-5051 http://www.fatcity.com
San Diego, California -- Mailing list and web hosting services
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