RE: recovery from RAW partitions
- From: "Powell, Mark D" <mark.powell@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 17 Jun 2008 09:52:55 -0400
We have used raw partitions for a long time. Generally raw partitions
provide 3 to 5% better performance than direct IO which is generally
better than the other available IO methods.
At the OS level you need to use 'dd' to backup/copy raw partitions or
use rman for you backups.
It makes little sense to use expandable datafiles built on raw
partitions which might be one problem your DBA has with using raw
partitions.
Also depending on the OS some OS's cannot define a raw partition on the
fly so you have to pay attention to your tablespace growth and plan
ahead. For some people holding DBA positions this is asking too much.
-- Mark D Powell --
Phone (313) 592-5148
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Bobak, Mark
Sent: Tuesday, June 17, 2008 12:13 AM
To: ricks12345@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: recovery from RAW partitions
Let's try this again. What does "I was talking to a DBA today who
insisted that performing a recovery with a RAW partition." mean? What
are you asking for agreement/disagreement on?
As to the performance improvement, if any, of raw devices, well, as with
many things, it depends.
Personally, I use raw partitions for the following reasons:
- AIO and DIO capable
- no memory wastage caching datafile blocks in filesystem cache
- Sys admin staff is comfortable w/ raw partitions
- In my environment, there's no downside
-Mark
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Rick Ricky [ricks12345@xxxxxxxxx]
Sent: Monday, June 16, 2008 11:01 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: recovery from RAW partitions
I was talking to a DBA today who insisted that performing a recovery
with a RAW partition. He didn't really explain why. Does anyone agree
with this? If so why? He also said that RAW partitions only give about a
2% performance improvement. If so, why would you want to use them (other
than with voting disks and OCR in RAC).
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