Re: ASM Filter Driver Performance

On 01/25/2018 08:36 PM, Jared Still wrote:
>
> Interesting that there would be an expectation for me (or anyone) to
> be able to explain just what Oracle Developers did to improve their code.

Sorry, I cannot accept this. If such an improvement is made, I need to know just the basic facts about how and why. It's not your fault, Oracle simply doesn't produce the necessary documentation any more.

> As I have already written, ASM Filter Driver is very new. Any bugs
> in the driver mechanism can bring your instance, and therefore
> your database, down. Such outlandish claims do not convince me on
> the merit of using filter driver.
>
> Outlandish claims?
>
> No claims were made, just results of performance tests.

Claim is that there is 20% improvement. And I find that number very suspicious without some background information. No disrespect to you, but what would that say about the RAC as a product if 20% performance improvement can be achieved by simply changing the disk drivers?

As for "more details on Hotsos and IOUG",  I am awaiting for a MOS document which would explain better performance and the basic principles behind achieving it. ASMLib is a raw disk driver. The only way such a large performance improvement can be made is to use block devices and OS cache, which has a read-ahead and write back mechanisms. That, on the other hand, has ramifications for the commit processing and ACID compliance. This is not just a performance question, we are talking about the basic principles here. As you said, filter drivers are very new. And I will ignore them until some reliable documentation is produced. The performance numbers you produced are alarming.

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217


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