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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Multiple Datafiles and performance?
I don't know of any advantage to uniform datafile sizes. Back in the day some DBAs preferred uniform datafile sizes so that they could easily move datafiles from disk to disk to balance physical IO. With modern disk configurations this strikes me as more work than it's worth. However, if you really, really need that last little bit of "umph" then it is a consideration.
4x1 or 2x2 - 4x1 has more "things" to keep track of. Otherwise, to the best of my knowledge it's not an issue.
If a datafile autoextends to the 2G mark, under certain service pack releases of Win2k the datafile becomes corrupted. As I remember the discussion, MS had fixed one of their disk IO dlls to work over the 2G mark but it the datafile size was under 2G the disk IO was handled by a program that could not handle growing to 2G. So if the datafile was over 2G you wouldn't run into the problem. MS does have upgrades to fix the problem. Has your SA applied them?
I've been reading various white papers about RAID 10 vs. RAID 01
(mirror-then-stripe vs stripe-then-mirror). I've heard good arguments on
both sides and I hope that the experts can come to a consensus. Only RAID
manufacturers seem to be pushing RAID 5.
Right now Oracle's recommendation is SAME (Stripe All, Mirror Everything). It is not the absolutely optimal situation but it will provide adequate performance in most situations.
HTH
"Dave Phillips"
<dphillips To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
@gasper-corp.com cc:
> Subject: RE: Multiple Datafiles and performance?
Sent by:
ml-errors
08/07/2003 11:24
AM
Please respond
to ORACLE-L
Gee, that question sounded a whole lot better when I wrote it yesterday
than it did this morning when I saw it. :) Maybe I should be a little more
vague.:)
The problem is there are a couple of things I am trying to accomplish. We
have clients that use our application that have specific performance issues
which I am working to improve. The other issue is to provide recommendation
to development/tech staff on initial setup of
database/tablespaces/datafiles etc.., along with hardware recommendations
for our application.
So, that being said, I'll try and ask better questions.
The environment is W2K, Oracle 8.1.7.2 or higher
All tablespaces are LMT
Most disk config's are 1 (or 2) Raid 1 along with a Raid 5 for basic
systems.
Most operate application 24/7
Questions:
For future apps I am pushing for optimal recommendations that go for more raid 1 sets or raid 10 over the Raid 5. This should allow for more flexibility for spreading out the i/o.
Thanks for your patience and all the help.
David Phillips
Support DBA
BAARF Member #30
-----Original Message-----
Sent: Thursday, August 07, 2003 9:59 AM
To: Multiple recipients of list ORACLE-L
Win2K. If you decide to increase the filesize, do it to more than 2G
(doesn't have to be by much). Of course, you didn't mention autoextend so
this may not be an issue.
Also, just how many physical disks do you have? Logical disks are not the issue. If you're going to get any increased performance you should be putting the second datafile on a second physical disk. Any how come you're not using some sort of RAID device (or don't you have your logical drives striped across your physical drives)?
There is no easy answer to your question without an understanding of the reality of your disk layout.
"Fermin Bernaus"
<fbernaus To: Multiple recipients
of list ORACLE-L <ORACLE-L_at_fatcity.com>
@sammic.com> cc:
Sent by: Subject: RE: Multiple
Datafiles and performance?
ml-errors
08/07/2003 08:05
AM
Please respond
to ORACLE-L
In my experience, spreading datafiles across volumes
As for the file size, I can not say because I have not tested it, but I think it should have no real impact compared to splitting it. Reorganizing the database regularly is a better way to optimize performance.
..............................................Fermín Bernaus Berraondo
..............................................
-----Mensaje original-----
De: Dave Phillips [mailto:dphillips_at_gasper-corp.com]
Enviado el: miércoles, 06 de agosto de 2003 22:14
Para: Multiple recipients of list ORACLE-L
Asunto: Multiple Datafiles and performance?
Oracle 8.1.7.4
Win2k
What is the consensus on datafile sizing and the impact/overhead multiple datafiles have on performance?
For example, if I have one 2.5g datafile, and three 1g datafiles, and I
need more space, would it be better to increase the size of the 1g to
2g or add another 1g datafile?.
Is it better to keep them all uniform in size?
I would think having multiple datafiles that could be spread across drive volumes would be beneficial, am I wrong? (Wouldn't be the first time :)
TIA
David Phillips
Support DBA
Gasper Corp.
BAARF member #30
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Dave Phillips INET: dphillips_at_gasper-corp.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-LReceived on Thu Aug 07 2003 - 11:09:24 CDT
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