RE: World premier performance of the BAARF party logo

There is no question that RAID 10 performs better than RAID 5. But it highly questionable that every Oracle database requires RAID 10 for all its data files. Though I'd never consider putting redo logs on RAID 5

Also, often the DBA has no clue about what type of disk throughput is needed. Not because the DBA is ignorant, but extracting the information from the potential users which enables the DBA to arrive at an estimate is far too often close to impossible.

Ian MacGregor
Stanford Linear Accelerator Center
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Sent: Sunday, June 15, 2003 11:14 AM
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Mladen - I would propose another theory. Please consider this rant for entertainment value, and hopefully to consider a book on this topic.

   Usually companies request bids from several vendors. If you as a storage salesperson always bid RAID1+0, you will always be underbid by your competitors, receive no commissions, and in the end be fired. If you always bid RAID5, you will probably receive some business, some commissions, and keep your job. Now, pretend I'm a storage system salesperson. Which system am I going to specify to the customer? Now, if the customer insists on purchasing RAID1+0 or whatever, I'll probably argue a little because I've been stung before where I was suckered into bidding RAID1+0 and then my ignoramus competitor just blindly quoted RAID5 and when it bubbled up to the V.P. he asked "why are you going with the more expensive vendor"? And trying to quote a salesperson isn't a good move at that point.

   I thought Rachel had a good point on this topic awhile back. If you are a top-notch consultant that is often called in to solve performance problems, you have often cured them by switching from RAID5. So you have a lot of confidence in it. But if you are the lowly on-site DBA just trying to hang onto your job in the political turbulence, you usually don't have enough facts to challenge the system administrators who trust their storage vendors a lot more than a DBA that couldn't actually configure a storage system to save his or her life.

   So suppose I do try to challenge the system administrators. I say that RAID1+0 will write faster than RAID5. The reply is "okay how much RAID1+faster?" I
mumble that I've never seen any actual figures published anywhere. He or she says maybe at the low level there is a slight advantage to RAID1+0, but with a gig of battery-backed cache that won't be true. Or he or she asks "What does Oracle recommend?". And on it goes.

   Okay, I'm being provocative here. But how do I, a lowly DBA, prove which is faster? Should I talk my system administrator into going to the trouble of configuring a system both ways and run some tests? What type of tests would be most useful? If I choose the wrong test, and RAID5 looks just as good as RAID1+0, I'm sunk. Then for years to come when I try to make a point at a meeting someone will say "yeah, is this another RAID1+0 theory?"

Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
[EMAIL PROTECTED] -----Original Message-----
Sent: Sunday, June 15, 2003 2:49 AM
To: Multiple recipients of list ORACLE-L

RAID-5 microkernel has more lines of code then Oracle7? Wow! This is an astonishing piece of information and if it wasn't coming from you, I'd dismiss it as yet another conspiracy theory.

On 2003.06.15 01:44, Cary Millsap wrote:
> > Meanwhile I have never understood why storage vendors would prefer
> > selling RAID5 over RAID10.
>
> ...Because if they don't sell RAID5, they don't recover the R&D costs
> of creating a RAID5 microkernel that has more lines of code than the
> Oracle7 executable. I'm not kidding.
>
>
> Cary Millsap
> Hotsos Enterprises, Ltd.
> http://www.hotsos.com
>
> Upcoming events:
> - Hotsos Clinic 101 in Dallas, Washington, Denver, Sydney
> - Hotsos Symposium 2004, March 7-10 Dallas
> - Visit www.hotsos.com for schedule details...
>
>
> -----Original Message-----
> Niall Litchfield
> Sent: Thursday, June 12, 2003 12:05 PM
> To: Multiple recipients of list ORACLE-L
>
> Jared writes
> > At the meeting last week I wore my 'No RAID 5' hat.
> >
> > Those of you at IOUG 99 in Denver may have seen it, I
> > wore it every day there. ;)
>
> I'm curious now. Pictures required.
>
> Meanwhile I have never understood why storage vendors would prefer
> selling RAID5 over RAID10. More disks=more profit surely? Also 10 > 5
> therefore self evidently twice as good for all applications. Meanwhile
> we have this strange situation where performance consultants are
> publicising the fact that you have less need for performance
> consultants with RAID10 than with RAID5.
>
> Niall
>
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-- 
Mladen Gogala
Oracle DBA
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