Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: Oracle performance on different drive types.

Re: Oracle performance on different drive types.

From: Doug Carter <dcarter_at_tui.com.au>
Date: Tue, 5 May 1998 16:33:22 +1000
Message-ID: <6imbrh$s23$1@reader1.reader.news.ozemail.net>


Eric,

Eric Ladner<CLAD_at_PASMS.CHEVRON.COM wrote in message <354E1E01.3E97A8C3_at_pasms.chevron.com>...>Hi all,
>
>Does anyone have any numbers or gut feelings of Oracle performance on
>different drive configurations? I'm specifically looking for
>comparisons between regular drives, striped drives and RAID 5 drives.
>
>Is there a performance hit or gain for these groups?

In the last 3 years I have come in contact with probably 80 Oracle systems of which maybe a third used RAID 5. I have little but contempt for its' use in an Oracle Database environment. As far as I am concerned it is a poor mans excuse for data protection. The amusing thing is in my experience the RAID systems have far more problems than those using single disks.

Unless they are cached up to the hilt a large number of updates can result in slow performance - and while happily fixing themselves after a disk loss I have known some of them to stop responding to system data requests. (For which many sites then rebooted - corrupting the entire set, but that’s another story).

Stripping is a better option than RAID 5 (especially for performance) but I would really recommend either full mirroring or intelligent use of single disks. The selection should depend on access requirements (not price!). Go for single disks if the users a happy for recovery time to include hours of down time - or mirroring if the system must be up and running as quickly as possible. (As much as that is possible to guarantee!)

On using single disks - by placing non critical tablespaces together (index, temporary etc) you can create 'non critical' disks who's loss does not leave the system inaccessible. This can cut the disk single point of failures by half.

Another nice thing about single disks over raid - a corrupt raid disk contains nothing readable (it is not an entire image). I have been able to salvage almost all the data from disks with errors by completing straight dd copies to a replacement.

The easiest way to put this is you get what you pay for - but not even my worst enemy deserves RAID 5. (BTW - RAID seems ok when used in an environment far less demanding than a database)

Cheers,

Doug Carter [dcarter_at_tui.com.au]
Database Administrator
TUI Consulting
Melbourne, Australia
http://www.tui.com.au

(Notice I’m a little against RAID 5 – comes from to many late nights restoring entire systems) Received on Tue May 05 1998 - 01:33:22 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US