RE: asm vs raw - the smackdown

It's also worth noting that effectively, ASM *is* raw, since the Oracle
database still does I/O directly to block devices.  ASM just provides
that handy dandy metadata layer.  Does your vendor have any (good)
reasons why they don't want you to use ASM, or for that matter, a
filesystem?

Thanks,
Matt

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Jeremy Schneider
Sent: Wednesday, May 27, 2009 2:00 PM
To: jifjif@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: asm vs raw - the smackdown

~Jeff~ wrote:
> does anyone know of any papers or study comparing ASM vs raw
> performance?   We have a vendor deadset on raw, and the DbAs would
> rather not have to deal with that!
From metalink note 754305.1, accessed today:
==> In release 11.2, the Oracle installer and DBCA (Database
configuration assistant) will no longer support raw/block devices for
database files.
==> As stated in metalink note <578455.1>, Oracle plans to fully
desupport RAW/Block device storage effective with the next major release
following 11.2. At this time, customers will need to migrate any data
files stored on RAW/Block devices to ASM, a cluster file system, or NFS.
Thus, we recommend new databases not be deployed on RAW/Block devices.

I couldn't access metalink note 578455 but it is also mentioned here:
http://askdba.org/weblog/?p=154

Also, just a technicality, but if you're on Linux then raw access has
long been deprecated in favor of direct block access.

I wouldn't expect to see too much difference in performance since ASM is
essentially accessing the devices in a "raw" manner.  But there are
countless other reasons to choose ASM above raw. And I really can't
think of a single good reason to choose raw above ASM today.  If it were
me, I'd continue to strongly argue with the vendor.

-Jeremy

-- 
Jeremy Schneider
Chicago, IL
http://www.ardentperf.com

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