Re: Getting the best out of new server hardware: a disk setup for Oracle database

On 2006-06-14, Mladen Gogala <gogala_at_sbcglobal.net> wrote:
> On Tue, 13 Jun 2006 19:01:35 +0300, Heikki Siltala wrote:
>
>> No RAC here. I found ASM to be the easiest way to implement S.A.M.E on
>> this setup where we have six independent RAID 1+0 sets directly
>> connected to the server. ASM will stripe everything over the six sets
>> and quarantee that there are no "hot spots". This sounds much simpler
>> than putting ext3 on the RAID sets and then try to manually distribute
>> the IO load over the sets by manually relocating Oracle datafiles
>> between the sets.

        Of course it seems simpler. It's not even the simplest ext3 based option available. If you put two fighters in the ring together and then handcuff one of them, of course the manacled one will get pummeled.

>
> Let me dispel the myth of re-balancing by an email message from Scott
> Heisey, a guy who might know a thing or two about RAC, ASM and such.
> The message is from another Oracle forum:
>
> Subject: Re: ASM Record Deletions
> Date: 06/13/2006 07:26:17 PM
> From: Scott <oraracdba_at_yahoo.com>
> To: smishra_97_at_yahoo.com, oracle-l_at_freelists.org
>
> Sanjay, ASM works at the file level not at the table
> level. If you delete records the space in ASM does not
> change so there will be no re-balancing. Re-balancing
> will or should occur if you add, expand or drop
> tablespaces/datafiles.
>
> Scott
>
> --- Sanjay Mishra <smishra_97_at_yahoo.com> wrote:
>
>> Hi
>>
>> If I have 10 millions records in a table and if I
>> drop the table or delete 1 million records and if
>> ASM_POWER_LIMIT to > 0, Is it going to rebalance the
>> Disk space among all Disks used in the Diskgroup.
>> This table is currently having 50G space.
>>
>> TIA
>> Sanjay
>>
>
> Both Sanjay Mishra and Scott Heisey are extremely well known names,
> they are no dilettantes. From that perspective, I/O load balancing is
> not a particularly useful feature, unless you plan on dropping your files
> daily, which would be a very novel approach to database administration.
> My advice to you is to contact everybody who's using ASM in production
> and ask them for experience. I expect you to find a s*tload of people
> using ASM in production, so you will have no problem finding references.
>

-- 
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