Re: stripes or separate spindles

My take on the trade-off between striping and RAID-1 is simple I believe in my ability to evenly distribute the total I/0 load across my available spindles better than I trust the hardware controller to do so. I always only use RAID-1. I simply do not accept the premise that RAID-0 (striping) data will result in better performance than RAID-1.

When using striped volumes to hold Oracle datafiles, you have minimal control WRT exactly what data resides on which spindle. In theory & in round numbers a RAID-0 volume consisting of 3 spindles should be able to sustain & support three times the I/O rate of a single volume and an I/O rate equal to 3 RAID-1 volumes. However situations can occur where the "hot data" on a RAID-0 volume all resides on a single spindle and the effective I/O rate is the same as a single RAID-1 volume.

Simply put I/O throughput is a ZERO-SUM game. There is a maximum rate which can be met & sustained, all due to physical limitations inherent within the existing design & implementation. This means that striping (RAID-0) can NEVER give better than with RAID-1. I say this because on RAID-1 the data can be distributed across the volumes the same way it gets distributed by the RAID-0 controller or software volume manager & so equal performance by RAID-1 & RAID-0 can always be obtained.

HTH & YMMV! Ruth Gramolini wrote:
>
> There will be 2 controllers on the box. There will be one huge file system
> for the databases. It will have 7mirrored 36gig spindles in the space.
>
> Ruth
> ----- Original Message -----
> To: "LazyDBA.com Discussion" <oracledba_at_lazydba.com>
> Sent: Wednesday, September 26, 2001 3:21 PM
>
> > I would be curious as well. Is it dependent on the number of controllers?
> > Is one big /u01 better if you bind the disks together and one controller?
> > Or use /u01 thru /u04, partition and stripe with one controller?
> >
> > Brian
> >
> > ----- Original Message -----
> > From: John Lewis <jlewis_at_punchnetworks.com>
> > To: LazyDBA.com Discussion <oracledba_at_lazydba.com>
> > Sent: Wednesday, September 26, 2001 3:06 PM
> > Subject: RE: stripes or separate spindles
> >
> >
> > > I'd like to see the answers here. Life used to be so simple
> > > before Raid 0 thru N
> > >
> > > It was nice to be able to see the writes to a particular disk
> > > on a distinct controller.
> > >
> > > (Okay, I'll stop. Sorry for that little walk down memory lane)
> > >
> > > -----Original Message-----
> > > From: Ruth Gramolini [mailto:rgramolini_at_tax.state.vt.us]
> > > Sent: Wednesday, September 26, 2001 12:02 PM
> > > To: LazyDBA.com Discussion
> > > Subject: stripes or separate spindles
> > >
> > >
> > > Dear Fellow Listers,
> > >
> > > We are going to get new servers with much more space. We will have 8
> > 36gig
> > > disk drives, all mirrored. My question is: should I put my data,
> index,
> > > temp, etc tablespaces on separate spindles or stripe them over all
> > spindles?
> > >
> > > Any thoughts would be helpful. My sys admin says that striping across
> all
> > > spindles will get better performance.
> > >
> > > Thanks in advance,
> > > Ruth B. Gramolini
> > > ORACLE & DB2 DBA
> > > VT Dept. of Taxes
> > > ph# 802.828.5708
> > > fax# 802.828..3754
> > > rgramolini_at_tax.state.vt.us
> > >
> > >
> > > --------
> > > Oracle documentation is here:
> > > http://tahiti.oracle.com/pls/tahiti/tahiti.homepage
> > > To unsubscribe: send a blank email to oracledba-unsubscribe_at_LAZYDBA.com
> > > To subscribe: send a blank email to oracledba-subscribe_at_LAZYDBA.com
> > > Visit the list archive: http://www.LAZYDBA.com/odbareadmail.pl
> > > Tell yer mates about http://www.farAwayJobs.com
> > > By using this list you agree to these
> > > terms:http://www.lazydba.com/legal.html
> > >
> > > --------
> > > Oracle documentation is here:
> > http://tahiti.oracle.com/pls/tahiti/tahiti.homepage
> > > To unsubscribe: send a blank email to oracledba-unsubscribe_at_LAZYDBA.com
> > > To subscribe: send a blank email to oracledba-subscribe_at_LAZYDBA.com
> > > Visit the list archive: http://www.LAZYDBA.com/odbareadmail.pl
> > > Tell yer mates about http://www.farAwayJobs.com
> > > By using this list you agree to these
> > terms:http://www.lazydba.com/legal.html
> > >
> >
> >
> > --------
> > Oracle documentation is here:
> http://tahiti.oracle.com/pls/tahiti/tahiti.homepage
> > To unsubscribe: send a blank email to oracledba-unsubscribe_at_LAZYDBA.com
> > To subscribe: send a blank email to oracledba-subscribe_at_LAZYDBA.com
> > Visit the list archive: http://www.LAZYDBA.com/odbareadmail.pl
> > Tell yer mates about http://www.farAwayJobs.com
> > By using this list you agree to these
> terms:http://www.lazydba.com/legal.html
> >
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Ruth Gramolini
> INET: rgramolini_at_tax.state.vt.us
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
> (or the name of mailing list you want to be removed from). You may
> also send the HELP command for other information (like subscribing).

-- 
Charlie Mengler                            Maintenance Warehouse  
charliem_at_mwh.com                           10641 Scripps Summit Ct.
858-831-2229                               San Diego, CA 92131    
United WE Stand!                           Justice WILL Be Served!
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Charlie Mengler
  INET: charliem_at_mwh.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).