Re: Best method to move Filesystems to RAW Devices.

From: Nat <Nat2710_at_hotmail.com>
Date: Fri, 20 Sep 2002 06:18:28 -0800
Message-ID: <F001.004D4CE6.20020920061828@fatcity.com>

Dennis,

Thanks for the reply. We have not done any benchmarks to find out if there is any performance
gain. The main reason for moving to raw devices is to convert our existing database to function on OPS
environment and then eventually to 9i RAC.

After we move on to raw (without OPS), may be I will post to the list what is the performance increase/decrease, problems encountered.. etc..etc..

Thanks,

Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Thursday, September 19, 2002 5:23 PM

Nat - I'm assuming you can connect raw devices to your existing system. Myself, I would create new tablespaces and datafiles on the raw devices. Preferably you will use LMT with uniform extents. Then I would use CREATE TABLE AS SELECT NOLOGGING to move the data. Personally I prefer to first rename the original table to something like table1_sav and then create table1 as select * from table1. Eventually when you've checked everything out (taken a backup, backed up the control files) you will drop the table1_sav. But your applications can immediately use the new table with no changes.

Then you'll have to recreate indexes, but I don't know any way around that.

What performance increase is your benchmarks telling you that you will experience? Oracle had an interesting white paper on their site. In effect it discussed the question "why do all benchmarks show raw much faster than cooked, but nobody sees that sort of performance in production?".

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com <mailto:dwilliams_at_lifetouch.com>

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

Sent: Thursday, September 19, 2002 1:39 PM To: Multiple recipients of list ORACLE-L

We are planning to move to raw devices for all our existing file systems. Our database size is around 400 Gig. What is the recommended method that you guys feel is best as far as time
required to convert and ease of conversion.

We feel we cannot use export - import as this may take more time for conversion..
I checked many documents to find out the best method, there are few suggestions to use RMAN to convert to raw. seems it is fastest. At this point we have not configured RMAN on our databases so this suggestion seems to be of no use for us.

Please let me know, if any of you went through this exercise and any suggestions and tips will be more beneficial,

Thanks in advance,
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Author: Nat
INET: Nat2710_at_hotmail.com

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Author: DENNIS WILLIAMS
INET: DWILLIAMS_at_LIFETOUCH.COM

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Author: Nat
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