Re: [dm-devel] Re: Is there a grand plan for FC failover?

Philip R. Auld
2004-02-12T16:05:52Z

Rumor has it that on Thu, Feb 12, 2004 at 04:28:41PM +0100 Arjan van de Ven said:
>
> > That size is based on the blocksize? Is there a way to set the block size higher than
> > 512 w/o mounting it? I've gotten really bad rawio performance on 2.4. since I have a
> > limit of 32 sg entries. When Rawio uses a 512 byte blocksize IOs are limited to 16K.
> >
> > Will this still be a problem in 2.6?
>
> If you code the driver right, it's not even a problem in 2.4 if you use
> a Enterprise Linux distro kernel.....
>

Hi Arjan, I think you know that I do use your Enterprise kernel :)

Can you please explain what "right" means in this case?

I've a hardware limit of 32 sg entries. When the blocksize is the default hardware
sector size of 512 I get commands of 32 separate 512 bytes scatter-gather entries.
This is deteremined at a higher level than my LLDD. What is there that I can do
about it in the driver?

Cheers,

Phil

--
Philip R. Auld, Ph.D. Egenera, Inc.
Principal Software Engineer 165 Forest St.
(508) 858-2628 Marlboro, MA 01752