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" <[EMAIL PROTECTED]>
> 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 <[EMAIL PROTECTED]>
> > To: LazyDBA.com Discussion <[EMAIL PROTECTED]>
> > 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:[EMAIL PROTECTED]]
> > > 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
> > > [EMAIL PROTECTED]
> > >
> > >
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> Author: Ruth Gramolini
> INET: [EMAIL PROTECTED]
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