[CentOS] DMA disabled on SATA disk with Core Duo/i955 machine (Inspiron 6400)

William Warren hescominsoon at emmanuelcomputerconsulting.com
Tue Oct 24 21:12:00 UTC 2006

I hve a PE sc430 running sata drives.  transfer rates are jsut fine and 
it show no DMA either.  I think the DMA transfers run just fine in sata 
and do not need to be enabled by default.  Also some disk tools in linux 
have not caught up to the sata revolution yet.  If your tests show low 
transfers then you have an issue.  I have the type of transfers during 
tests i expect so i think the tools are erroneously reporting dms off 
because they don't understand sata drives yet.

first last wrote:
> --- James Pearson <james-p at moving-picture.com> wrote:
>> On 23/10/06, first last <prelude_2_murder at yahoo.co.uk> wrote:
>>> I am trying to use CentOS 4 on this machine and it does not allow
>> me to
>>> set DMA to 1, it just says that it is not possible. I have tried
>>> updating to the latest release and it still won't work.
>>> I have searched for it on Google and there is a thread mentioning
>> the
>>> same machine and CentOS, but none of the solutions (-p, -X 12) seem
>> to
>>> work at all and there is no "it works!!!!!" message.
>>> Is there anyway I can get DMA working or will I have to wait for
>> CentOS
>>> 5? Will any of the "unsupported" kernels work? (I would try
>> Ubuntu's
>>> kernel on CentOS, as I am successfuly using that distribution, but
>> it
>>> is a bit stupid not to use SELinux and it probably wouldn't work
>>> either).
>> I don't think you can use hdparm on SATA disks?
>> I know some BIOS's allow SATA disks to look like IDE 'legacy' drives
>> (/dev/hdX) - if this is the case, then the OS may be using the
>> generic
>> IDE driver and it might not support DMA.
>> If this is what you are seeing, then you might want to turn off the
>> legacy or compatible mode in the BIOS and use the drives via /dev/sdX
>> ...
> I think this is the case, but there's no way to change the settings in
> the BIOS (that's dell for you). Any way to force the system to use SATA
> instead of P-ATA?
> Thanks
> Gabriel
>> James Pearson
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Isa 54:17  No weapon that is formed against thee shall prosper; and 
every tongue that shall rise against thee in judgment thou shalt 
condemn. This is the heritage of the servants of the LORD, and their 
righteousness is of me, saith the LORD.

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