On Wed, 11 Feb 2004, Andreas Janssen wrote:

> Hello
> 
> Darin Strait (<[EMAIL PROTECTED]>) 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


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