[lug] RH Linux download + hdparm

[Calvin Dodge]

On Thu, Oct 18, 2001 at 08:03:04PM +0000, Greg Horne wrote:
> DMA = 0
> Timing buffered disk reads:  64 MB in 13.35 seconds = 4.79 MB/sec
> DMA = 1
> Timing buffered disk reads:  64 MB in  6.75 seconds = 9.48 MB/sec

That's verra nice!

> Major improvment on my K6!  Slowed down the Pentium 200 by 1.07 MB/sec.  
> Does the DMA setting stay after running hdparm or do I have to make it 
> permanent elsewhere?  Thanks for all the info Calvin!

One does one's best.

I believe the setting stays until 1) a driver error, or 2) rebooting. Check out the hdparm manual (option "-k" in particular) to see about preserving the DMA setting during error recovery.

To make it permanent after rebooting ...

IIRC, old RH distros didn't have any pertinent configuration options built in (or maybe I just wasn't aware of them at the time - I've been using RH for about 3.5 years, so I was a Linux newbie when I first installed RH 5.1). On those systems I'd put the appropriate hdparm command in /etc/rc.d/rc.local.

At some point that config info WAS built in - the file /etc/sysconfig/harddisks was the place to go to set such hard drive options.

I _believe_ current kernels set DMA by default.

So ... what distro, version and kernel are you using?

Calvin

-- 
Calvin Dodge
Certified Linux Bigot (tm)
http://www.caldodge.fpcc.net