Re: ide-scsi with 2 drives
> > > /dev/hda hd
> > > /dev/hdb dvd writer
> > > /dev/hdc hd
> > > /dev/hdd dvd rom
> >
> > I have found mixing hd's & cd'd on the same IDE controller to cause
> > issues. I have even had issues with the position of the drives on the
> > ribbon cable, depending on the UDMA number of the device. I would start
> > with hd's on one cable & cd/dvd's on the other. Make sure your chipset
> > is supported by kernel. This may be old info as I have been running
> > scsi mostly.
>
> But then performance will take a hit.
Not necessarily. As usual, it depends on the usage pattern. Here's my
understanding of the performance trade-off:
An optical drive (slow) running on the same IDE channel as a hard drive
(fast) will slow down data transfer to and from the hard drive, when the
optical drive is operating (by forcing a lower DMA mode?). So in the
configuration above, if both DVD drives are operating at once-- say,
when making a direct disc-to-disc copy-- then both hard drives become
slow. Bad.
OTOH, if both hard drives are on the same IDE channel, then they may
compete with each other for the bandwidth on that channel. So again
this can slow things down.
So as far as just the performance goes-- leaving aside the original
question :) -- it just depends on how you're using your drives. If you
use both optical drives at once very often, then put them on the same
controller so they're not slowing down the hard drives. But if there's,
say, one optical drive that you don't use very much, then pair it on an
IDE channel with the hard drive that you want to get the most
performance from.
Of course this is all received lore-- stuff I read about or was told a
long while back. If someone can explain why I'm wrong, I'm all ears.
A.
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