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RE: Sizing - RAC, storage subsystem EMC

From: <>
Date: Mon, 26 May 2003 22:26:39 -0800
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Hi Dennis

I second that, It would be great to get someone to sit and design/publish a book of system design hardware (Sun, HP, Compaq, IBM, DELL etc) and storage designs from JBOD to SAN and list the experiences.

We can even have a nice case study section and list designs and configuration for companies like Oracle, Dell, Yahoo, French Telecom etc.

It will def go a long way of making designers see what others has done. Instead of all of us always starting from over and then trying to get buy in from a System Admin because we did the hard drives in the SAN as RAID 10 instead of his magic always performing cheap RAID 5.


George Leonard
Oracle Database Administrator
Dimension Data (Pty) Ltd
(Reg. No. 1987/006597/07)

Cell: (+27) 82 655 2466
Tel: (+27 11) 575 0573
Fax: (+27 11) 576 0573

You Have The Obligation to Inform One Honestly of the risk, And As a Person You Are Committed to Educate Yourself to the Total Risk In Any Activity! Once Informed & Totally Aware of the Risk, Every Fool Has the Right to Kill or Injure Themselves as They See Fit!

-----Original Message-----
Sent: 27 May 2003 02:57 AM
To: Multiple recipients of list ORACLE-L

Mogens - Now you're getting the entrepreneurial spirit! The other idea would be to follow in Cary's footsteps and detail your knowledge in a book. That automatically increases your credibility. :-)

    Seriously, that has been one of my complaints. We need a Configuring Hardware for Oracle book. There have been a few attempts. Alomari is the latest one as far as I know. Just a glossary of technical choices and what they mean to a DBA would be a good starting point. I think there are a couple of pitfalls:

Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.

-----Original Message-----
Sent: Sunday, May 25, 2003 11:57 PM
To: Multiple recipients of list ORACLE-L

I finally see my error. Why do I keep having high blood pressure about RAID-5/RAID-4/RAID-53/RAID-S decisions? Doesn't make sense...because:

More RAID-5 -> more performance and availability problems -> more performance and availability work -> more money to consultants -> higher profit -> more money to company owner -> sex & power to company owner

Best regards,

Mogens Nørgaard
co-owner of Miracle A/S (a consultancy which specializes in performance and availability problems)


Rachel - You make some excellent points. I am speaking to the situation

where the site doesn't have a performance problem. When there is a problem,

everyone is much more eager to accept suggestions.

      As you point out, the DBA usually doesn't buy hardware, so the

hardware people tend to take that as intruding on their responsibilities

with the intent of making them look bad. So they react defensively. And for

every reason you can quote that RAID5 is bad, they will provide a

countervailing reason why your information isn't valid. At least not with

their hardware configuration. And the hardware vendor is very helpful in

giving them information that will bolster their arguments. Then again, your

average DBA usually isn't a foremost expert in disk configurations.

        A consultant that is paid to come in and solve a performance problem

then leave doesn't face the longer-term issues that arise from making ones

colleagues look bad. My point is that there are some battles one wouldn't

want to win.

Dennis Williams

DBA, 80%OCP, 100% DBA Lifetouch, Inc. <>

-----Original Message-----

Sent: Friday, May 23, 2003 8:27 PM

To: Multiple recipients of list ORACLE-L

Here's the thing. Disks are cheap. Maybe. But buying 5 disks is still

cheaper than buying 10 disks. And it is NOT the people who actually

work with the disks (DBAs, Sysadmins, even developers) who have the

authority to order the disks.

You need places and floor space to put the disks as well. It's not like

you can just hang them from the ceiling.

And even more so these days, and it seems most especially in the US

companies, companies are trying to cut costs to the bone (we just went

through an exercise where we practically had to jump through hoops just

to get more memory for a production system which obviously needed the

memory). And cutting costs means as few disks as possible, means reuse,

consolidate and do without.

It kind of reminds me of one of the sayings my parents (who grew up

during the Great Depression here) have told me of that time: "use it

up, make it do, or do without"

we're in the "do without" phase


I'm beginning to think that we're having this wonderful discussion


RAID-5 time and again because the vendors keep coming up with


to prove that the general laws of nature don't apply to this



In the 50s we had a prime minister here in Denmark that said to the

assembled parliament: "If that's the facts, then I deny the facts".

Somehow you have to admire a guy like that.

Since disks are now cheap, how on Earth is it that we allow various

IO-vendors to bundle cheap disks, expensive cache which we won't


and stupid technologies like RAID-5 into a box called SAN/NAS or

whatever and charge 42 billion units of some real currency for it?

Why don't we take our swords and shotguns and AK-74s (that's the


calibre), and point them at them until they actually just bundle a


of inexpensive disks into RAID 1+0 which we ALL know is superior to

RAID-S, RAID-5 (notice how S looks like 5 - it's no coincidence).


superior to RAID 0+1 even. It doesn't require (the expensive) cache


One of my wonderful experiences was with a TelCo here, where the


kept saying that they should of course just add cache if performance

wasn't sufficient. When they finally reached the 32GB (yep,


giga-bytes) of cache alone, they gave up, ripped the stuff apart and

reconfigured it as RAID 0+1 and it finally performed on the small

writes. We all loved it - except possibly the disk-vendor, who kept

saying RAID-<some letter that resembles the number 5> was of course

fantastic, and that they shouldn't listen to all these bitter, old,

twisted Oracle people who just hated RAID-5 and the likes ... ahhh...

just because!

It's got nothing to do with Oracle or not. It's got to do with money



RAID 1+0 is the best you can buy.

RAID 0+1 is almost as good.

RAID 5 sucks - in all its disguises and permutations - compared to


or 1+0.

If RAID-5 is good enough for you, fine. But remember to test the


old restore of the backup and time it so that you're prepared if it

happens. It should of course take about four times as long as the


As Connor said (and Cary has said it in his excellent, but futile,

RAID-5 paper) it's when you really, really need disk performance that

RAID-5 will let you down.



Arun Annamalai wrote:     

Hi George.  

I would recommend go with Raid 5 and its not that one transaction

triggers that many writes as you have mentioned/calculated.

It is all buffered with recovery mechanism.  

Have you thought about Raid4(Network appliance) hardware. (I am no       


affliated with Network appliance, except that we use in our site.)

Most of the big names use them, such as

1, Yahoo. (you can see network appliance logo when you logout of       


yahoo email account)

2. Oracle

3. Southwest airlines.  

I mean Yahoo, Southwest Airlnes are all heavy transaction oriented

shop on a given per minute interval.

The most common overhead of SAN is that the throughput of the       


that connects your server to the san storage.  

Also, heard that Net App (best in NAS) is colloborating with       


(best in SAN storage) to get the best technology for storage and

thoroughput performance. But this might take a while or might       


be in the market. Check out with your local Hitachi or Netapp


Hope this helps.



      <> <>

    To: Multiple recipients of list ORACLE-L

      <> <>

    Sent: Tuesday, May 20, 2003 2:06 AM

    Subject: Sizing - RAC, storage subsystem EMC

    Hi all, hope you can give some input ideas.      

    I am in the process of designing a system for a client of ours       


    a proposal      

    The sizing information I have been given is as follows.      

    58.1 million tickets/day at 351 bytes per record. The record       


    complete populated (all columns filled to max) in a table and       


    analyzed. Average row size 351 bytes.

    =~ 19 GB/day. Raw data. Plus overhead (indexes, temp space,

    rollback, some other data etc) here and there I have requested       

5 TB.           

    We need to keep records for a month. Table design I am looking       


    is a date partition with a second level hash partition. This is       


    that I can move data in the oldest week/table space off line       


    write them to optical storage for possible retrieval at a later

    date (requirement).      

    Of course this will be on locally managed table spaces with       


    storage management for segments.      


    The database will be a Oracle RAC on Sun cluster 3       


    on 2 x Sun StarFire V880, 4 CPU's, 4 GB RAM each,

    Connected to an EMC SAN via Fiber Channel      

    I do not have more information about the EMC array at the       


    Hitachi has been mentioned. (excuse the spelling)      

    Question I have.      

    I have been asked how many writes the Database will be doing to

    the SAN per second.

    I have determined that I should expect about 2000       


    The table in question will have 2 indexes.      

    Now following rough guessing I said I should expect at least 16

    000 writes/second      

    This was done by say/assuming      

    2 writes for the redo log files (2 members)

    2 writes for the control files (2 control files)

    2 writes to index blocks

    1 write to undo table space block       

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Received on Tue May 27 2003 - 01:26:39 CDT

Original text of this message