Re: no dma on raid devices - bingo
On Tue, 27 Apr 2004, LeVA wrote:
> > > Is it normal, that I can not enable the dma mode on my cd devices
> >
> > some cd support dma .. others dont
> If I attache the dvdrom to the standard ide cable (ie. not raid) I can
> enable dma, so it supports it...
how do you know its supported ??
if from the output of hdparm -iv /dev/dvd that shows dma
turned on ... than okay ... otherwise, i doubt it is supported
since you're having problems
> > = do NOT mix ata-33 cdrom with ata-66/100/133 disks on the same
> > = ide cable
> > =
> >
> > > If I enable the dma on my dvd-rom, I can not
> > > read from the discs,
> >
> > are you talking about dvd or cdrom ???
>
> I don't think it matters...
that is the problem .... it does matter
> >
> > maybe your dvd-rom gets confused when told to do something it
> > doesnt know what to do
> >
> > > but if I disable the dma, the reading is very
> > > slow, and eats lot of cpu res.
> >
> > back to the bad idea of dvd on the same ide cable as hard disks ??
>
> Why it is a bad idea? I can safely mix the dvdroms with hdds on the
> standard ide cable, and on the raid cables either. My problem is only
> when I'm running some device on the raid cable, I can not enable the
> dma, although I could enable it, on the standrad ide cable.
again ...
- it does matter what the ide cable is
- it does matter if its cdrom or dvd
- it 100% mattters if there is a hard disks ( ata-66, ata-100 or
ata-133 ) on the same ide cable
and "raid cable" ???
- i still assume you're talking aobut software raid
as opposed to hardware raid
and not a scsi cables with scsi disks and scsi cdrom/dvd
and of course things will all work, if there is only 1 device
on the cables .. the toher guys is not repeatedly saying what, what,
what at ata-33 speeds when the hard disks are talking at ata-100 or
faster
in general .. insufficient into ... but am guessing you have
2 different speed devices on the same ide cable that slows
down your system to a crawl of 1 byte/sec transfers :-)
c ya
alvin
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