[CLUE-Tech] RH 7.2 DMA Woes

[Ed Hill]

Adam_Bultman at gmx.net wrote:

>>You can set/unset DMA at runtime with "/sbin/hdparm" and the kernel
>>parameters for DMA on IDE are described in:
>>
>>   /usr/src/linux-$VER/Documentation/ide.txt
>>
> Isn't there a danger of disk corruption?


Depends on your chipset.  See the kernel docs.  Older
chipsets (6mo or more) its very likely to work well.
Be careful with just-released chipsets and laptops.

>  Does it (hdparm) speed things up that much?


man hdparm

You should *read* and pay attention to the warnings.  Its
best to do the benchmarking in single-user mode.  Run it
with the -t/-T options both with and without DMA and
see the difference.  It can be significant--I've seen
30-100+% improvements in some of the tests.

hth,
Ed

-- 
Edward H. Hill III, PhD
Post-Doctoral Researcher    |  Emails:   <ed at eh3.com>, <ehill at mines.edu>
Division of ESE             |  URL:      http://www.eh3.com
Colorado School of Mines    |  Phone:    303-273-3483
Golden, CO  80401           |  Fax:      303-273-3311