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RE: Datfiles/logfiles layout

From: Mark W. Farnham <>
Date: Fri, 2 Jul 2004 10:57:01 -0400
Message-ID: <>

With only two arrays useful separation is a challenge.

You didn't mention where your archived logs go. If you're testing for throughput without archiving and you plan archiving for production, you will probably get a pretty big surprise when you turn on archiving. So even if you don't care about recovery, write the logs and through them away if you want meaningful measurements. Use the same level of block checking and all that stuff that you plan to use in production, or else you're not really testing.

Once you get everything else out of the way and you actually drive an i/o challenge to disk for inserts, it is usually useful to ping-pong the online redo logs so that "arch" is reading a different drive than "lgwr" is writing. While multi-user considerations may mute the advantage, this can make a big difference if a batch insert is dominating performance considerations. You need to use a multiple of logs that is divisible by the available number of locations that have independent throughput (it seems as if this is two in your case), and you need to create them in order to they alternate. If the archive destination is one of these arrays, it still may be okay, since arch will alternate pretty big slugs of read and write when it is operating on the same array or "stripe set."

You apparently have all your control files on the same array, which is probably not a good idea. Are you going with a single control file and relying on multiplexed disks (aka mirrors) when you get to production? Even in test I would not go with a single control file.

Finally, you *may* find that at steady state there is an imbalance in i/o signatures between tables and indexes, so you may want a table tablespace and an index tablespace on each array with the indexes of a given table counterposed with the indexes for that table. If your total production layout is as simple as your test, then it looks pretty good otherwise.


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

[]On Behalf Of Harvinder Singh Sent: Friday, July 02, 2004 10:24 AM
Subject: Datfiles/logfiles layout


We are setting up the oracle database machine and layout the files as following.=20
Env 10g on Win2k
2 cpu xeon processor box
2 raid array (raid 0, since this is testing) of 14 36G each and controller for each
Current layout:
Oracle software, control file, Rollback tablespace, temp tablespace, index tablespace(100GB file with extent sixe of 512MB) on 1 raid array (H:)
Table tablespace (100GB file with extent size of 1GB), redo logs on another array (I:)

We are testing insert performance where we are selecting from IOT table (on H:) and inserting into another table (on (I:) and its indexes on (H:)

Is this configuration looks ok or what are the changes that we can try?


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Received on Fri Jul 02 2004 - 09:53:31 CDT

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