Aldi,
I don't understand what your application engineer means by
"table scans and index look-ups are done separately". Indexes
are used to get to blocks of data in a table. So in an
application that has range scans, the indexes and the table
blocks are read one after the other and the overhead of moving
the disk head back and forth in seeking, can and will cause
significant I/O bottlenecks. I'd say in the least you will have
to separate DATA and INDX, but with 4 disks, data redundancy
becomes an issue.
So go back and negotiate with damagement for more disks, get a
good level of hardware support, document the risks and share it
with damagement, put the db in archivelog mode, take backups
that keep the Mean Time To Recover (MTTR) to an acceptable time,
configure your database buffer cache optimally (within reason)
to reduce I/O when possible, re-write any "SQL from the Crypt"
and pray your disks stay up. Hope you have more disks to place
your online redo logs, archived logs and other stuff. May the
force be with you....;-)
Cheers,
Gaja.
- Aldi Barco <ipal_at_hotmail.com> wrote:
>
> That's what I thought, splitting data and indexes.
> But, for better performance, application engineer recommends
> to locate both
> table and indexes accross 4 disks, because table scans and
> index look-ups
> are done separetely. What do you think ?
>
> Aldi
> Oracle DBA
>
> >From: David Barbour <DBarbour_at_connectsouth.com>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L
> <ORACLE-L_at_fatcity.com>
> >Subject: RE: 4 disks......
> >Date: Tue, 18 Jul 2000 11:06:07 -0800
> >
> >If you have two controllers - use two for data and two for
> indexes. What
> >about your binaries, redo logs and archive logs? Do you have
> sufficient
> >space to RAID1 the data and indexes? If not, despite the
> performance
> >issues, you may be better off going with RAID5 for the
> availability.
> >
> >David A. Barbour
> >Oracle DBA - ConnectSouth
> >512-681-9438
> >dbarbour_at_connectsouth.com
> >
> >
> >-----Original Message-----
> >Sent: Tuesday, July 18, 2000 11:26 AM
> >To: Multiple recipients of list ORACLE-L
> >
> >
> >Hi list,
> >
> >If you have 4 disks which one do you prefer :
> >
> >- use all disks for tables and indexes (and what kind of disk
> configuration
> >: striped, concatenated or raid5)
> >- use 2 disks for data and 2 disks for indexes
> >
> >Thanks for any clue.
> >
> >Aldi
> >Oracle DBA
>
>________________________________________________________________________
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> >--
> >Author: Aldi Barco
> > INET: ipal_at_hotmail.com
> >
> >Fat City Network Services -- (858) 538-5051 FAX: (858)
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> >Author: David Barbour
> > INET: DBarbour_at_connectsouth.com
> >
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> --
> Author: Aldi Barco
> INET: ipal_at_hotmail.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858)
> 538-5051
> San Diego, California -- Public Internet access /
> Mailing Lists
>
> To REMOVE yourself from this mailing list, send an E-Mail
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> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru')
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> also send the HELP command for other information (like
subscribing).
Gaja Krishna Vaidyanatha
Director, I-O Management Products
Quest Software Inc.
(972)-304-1170
gajav_at_yahoo.com
"Opinions and views expressed are my own and not of Quest"
Received on Tue Jul 18 2000 - 16:53:19 CDT
