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RE: World premier performance of the BAARF party logo

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Mon, 16 Jun 2003 07:06:31 -0700
Message-ID: <F001.005B230A.20030616055018@fatcity.com>


Mladen - Thanks for the clarification. Gee, does this mean no book? Well, maybe the movie would be some compensation.

Cary - Thanks always for your willingness to share your knowledge. Looking forward to your book.

Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
[EMAIL PROTECTED] -----Original Message-----
Sent: Sunday, June 15, 2003 2:24 PM
To: Multiple recipients of list ORACLE-L

Dennis, to tell the truth, writing in oracle is not a big problem, as long as the redo files are not on RAID-5. Everything else can reside on RAID-5 without a visible performance impact. Second, RAID-5 vendors like EMC and Hitachi usually offer two versions of non-volatile cache: write-through one which essentially performs prefetch and a genuine full cache which caches both read and write calls. The latter type of cache, which is very expensive,
is found on Symmetrix boxes only and not on former DG-Clariion boxes (talking
EMC here). These types of RAID-5 implementation are usually referred to as RAID-6 or RAID-S.
How to benchmark those? Well, the trick in benchmarking those systems is to do what one would never do with it's own system: put redo logs on RAID-5(6,S?), launch several threads of update intensive short transactions (OLTP mix) and count "user commits" from v$sysstat. Prior to that, establish a
baseline with RAID 1+0 and see what is the difference. See how many commits would RAID-5 box record during the same time as RAID-1+0 box and you'll know the difference in speed. Also, make sure to pull out one of the disks while system is working and see what's the impact of resilvering. <RANT>
As for the entertainment value, I would hope that Julia Roberts and Mel Gibson
would consider making a movie about the RAID-5 conspiracy. Julia would be a DBA trying to purchase a RAID box and Mel Gibson would be a honest RAID-5 salesman which would uncover a nasty EMC, IBM and Hitachi conspiracy. You can tell that it is a fiction because of the phrase "honest RAID salesman". The only problem would be to teach the two of them how not to sound "nucular".
</RANT>

On 2003.06.15 14:14, DENNIS WILLIAMS wrote:
> 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 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
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Niall Litchfield
> > INET: [EMAIL PROTECTED]
> >
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> --
> Mladen Gogala
> Oracle DBA
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Mladen Gogala
> INET: [EMAIL PROTECTED]
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: DENNIS WILLIAMS
> INET: [EMAIL PROTECTED]
>
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-- 
Mladen Gogala
Oracle DBA
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Mladen Gogala
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Author: DENNIS WILLIAMS
  INET: [EMAIL PROTECTED]

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Received on Mon Jun 16 2003 - 09:06:31 CDT

Original text of this message

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