Re: Mutliplexing control/redo files

From: Christo Kutrovsky <kutrovsky.oracle_at_gmail.com>
Date: Thu, 7 Oct 2010 22:28:08 -0400
Message-ID: <AANLkTimOvCyigTN9sr=hvGf=0aSN5JYU+SC80UG=WZCb_at_mail.gmail.com>



To all using ZFS and Oracle and saying ZFS is memory hungry.

ZFS is just as memory hungry as any other filesystem. It uses all available memory for caching. Exception to that is advanced features such as dedup, which can be 'memory hungry' in the true sense. And anyone using Oracle should NOT be relying on ZFS caching and giving all possible memory to Oracle.

As per file and directory layout, why not use OMF (Oracle Managed Files). There is no need for one to be bothered with this information.

In terms of physical design, the whole zfs concept is to forget about mountpoints, and instead fully rely on nested filesystems. Oracle does not need ZFS. As closer to raw as possible is ideal for Oracle (with ASM). Oracle also has most useful features ZFS offers such as snapshots (flashback database) and cloning (standby/dataguard/incremental backups).

If you have to use ZFS, remember the following very important performance configurations
- configure REDO and backup (including archivelogs) with default ZFS block size (128k)
- configure DATA and controlfiles to match database block size - this is critical
- Reduce the maximum amount of memory the ARC (zfs file cache) can use. Give as much as possible to Oracl. Don't cache in filesystem

There are other tuning aspects, but these are the main ones.

And one thing to remember - RAIDZ is not RAID5 - you get the IO capacity of a single spindle, not the combined.

-- 
Christo Kutrovsky
Senior Consultant
Pythian.com
I blog at http://www.pythian.com/blogs/

On Thu, Oct 7, 2010 at 1:04 PM, girlgeek <girlgeek_at_live.com> wrote:


> their use of 'large' and 'small' with no clue of what large or small
> actually means.
> -Claudia
>
> On 10/7/2010 9:48 AM, Rodd Holman wrote:
>
>> What does it mean "large db" ?
>>
> --
> http://www.freelists.org/webpage/oracle-l
> X-ecartis-version: Ecartis v1.0.0
> Sender: oracle-l-bounce_at_freelists.org
> Errors-to: oracle-l-bounce_at_freelists.org
> X-original-sender: girlgeek_at_live.com
> Precedence: normal
> Reply-To: girlgeek_at_live.com
>
> List-help: <mailto:ecartis_at_freelists.org?Subject=help>
> List-unsubscribe: <oracle-l-request_at_freelists.org?Subject=unsubscribe>
> List-software: Ecartis version 1.0.0
> List-Id: oracle-l <oracle-l.freelists.org>
> X-List-ID: oracle-l <oracle-l.freelists.org>
> List-subscribe: <oracle-l-request_at_freelists.org?Subject=subscribe>
> List-owner: <mailto:steve.adams_at_ixora.com.au>
> List-post: <mailto:oracle-l_at_freelists.org>
> List-archive: <http://www.freelists.org/archives/oracle-l>
> X-list: oracle-l
>
>
>
-- Christo Kutrovsky Senior Consultant Pythian.com I blog at http://www.pythian.com/blogs/ -- http://www.freelists.org/webpage/oracle-l
Received on Thu Oct 07 2010 - 21:28:08 CDT

Original text of this message