Re: My drive only operates in UDMA2?

[Dhiraj <dheerubhaipompom@yahoo.com>]

I had the same problem and I passed the parameter idebus=66, and it 
seems that my transfer rate increased from 20 MB/s to 30 MB/s. Is it 
very wrong to do this ? I wouldn't say I am using a server board. It is 
a very cheap KT133 board. I haven't had any problems on my system for a 
while but it seems like I should remove that parameter.
I am using a Seagate barracuda 80 GB ATA 100 HDD with Red Hat 7.2
My drive was previously in ATA33 mode and now it is in ATA 100 mode. 
I'll check about this "blue end" of the cable thing.

Alvin Oga wrote:
> On Wed, 11 Feb 2004, Andreas Janssen wrote:
>
>
> > Hello
> >
> > Darin Strait (<darin_strait@yahoo.com>) wrote:
> >
> >
> > > I'm troubleshooting something that has been bugging me for a while...
> > >
> > > Why does my drive seem to run only in UDMA2 and only do about 19.50
> > > MB/s, according to hdparm? Everyone else always seems to have a faster
> > > drive than me, so I'm assuming that I'm misconfiguring something and
> > > it's not my hardware.
> > >
> > > I have fiddled with idebus=66 in my grub menu.lst, but it has never
> > > seemed to have an effect.
> >
> > Please don't change that parameter if you don't really know what it
> > does. idebus is the speed in Mhz that the IDE bus uses. This has
> > nothing to do with ATA33 or ATA66. The ATA numbers name the theoretical
> > data throughput in MB/s. Unless you use some server mainboard your
> > system  very probably only supports a bus speed of 33 MHz.
>
>
> or risk losing everything on disk... not a biggie ... a good way
> to test backups :-)
>  
>
> > > I have an i810e motherboard and I'm running 2.6.2 (other kernel
> > > versions have had similar results). I have a Western Digital WD1200BB
> > > drive, the specs are as follows:
> > >
> > > [...]
> > > - Mode 5 Ultra ATA 100.0 MB/s
>
> that'd tell me that the disk is capable of udma5...
>
> but the mb is NOT recognizing it ...
> 	- check your bios ...
> 	- check your cables as andreas said - use the 80conductor cable
> 	- do NOT use round cables
> 	
>
> > > DMA modes:  mdma0 mdma1 mdma2
> > > UDMA modes: udma0 udma1 *udma2
>
> something is seriously broken ... on your system ...
>
>
> > > [...]
> > > * signifies the current active mode
> >
> > No. It signifies the mode that is used /if/ DMA is activated. If you
> > switch of DMA it will still tell you *udma2.
>
>
> and dma is enable so its good ... but the hdparm says it doesnt
> support udma3/4/5 ... 
> 	- either the specs is wrong or the bios is broken 
>
>
> > > Timing buffer-cache reads:   288 MB in  2.02 seconds = 142.31 MB/sec
> > > Timing buffered disk reads:   58 MB in  3.01 seconds =  19.27 MB/sec
> >
> > My guess: wrong type of cable. Make sure it can do more that udma2.
>
>
> but for udma2, something is seriously broken on your system
> ( you're at high risk to have your disk trashed )
>
> 	http://www.Linux-1U.net/Disks/
>
> 	udma2	-  13MB/sec ( whacky new xfer vs PIO modes )
> 	udma3	-  16MB/sec
> 	umda4	-  33MB/sec
> 	udma5	-  66MB/sec
> 	udma6	- 100MB/sec
> 	udma7	- 133MB/sec
>
> 	
> have fun
> alvin