Master or slave? Primary or secondary?

I'm getting set to put a larger drive in a machine.

It did have hda = main disk, hdb = CDrom, hdc = DVD-R(W).

The added drive could likely have content that I want to write to DVD. So
whereas it would be easiest to put the next drive on hdd, I'm wondering
how that would affect performance, i.e., DVD writing speed. (It's a 1.3MHz
machine.) And does "ide-scsi" help the situation at all, or am I still
impeded by the IDE controller, even though using SCSI emulation. Any
thoughts on where to put my drives would be welcome.

--
Dave Brown Austin, TX

On Wed, 30 Jul 2003 20:02:36 GMT, Dave Brown staggered into the Black
Sun and said:
> I'm getting set to put a larger drive in a machine.
> hda = main disk, hdb = CDrom, hdc = DVD-R(W).
>
> The added drive could likely have content that I want to write to DVD.
> So whereas it would be easiest to put the next drive on hdd, I'm
> wondering how that would affect performance, i.e., DVD writing speed.

Badly, since IDE devices don't share the bus well at all. Copying
things from /dev/hdc to /dev/hdd is much slower than copying things from
/dev/hda to /dev/hdc . Put your disks on one channel and your
CD/DVD devices on the other channel. I'd switch the CD-ROM to /dev/hdd
and put the new disk in at /dev/hdb. You'll have to make sure the
/dev/cdrom link is correct (pointing to /dev/scd1 or /dev/hdd, most
likely) but that's it, and you'll only have to do that once.

> (It's a 1.3MHz machine.)

Seriously retro, dude. (The original IBM PC ran at 4.33MHz. I Think
You Meant 1.3 GHz or 1300 MHz, right?) Processor speed is not the
problem here; I/O is.

> And does "ide-scsi" help the situation at all, or am I still
> impeded by the IDE controller, even though using SCSI emulation.

"hdX=ide-scsi" merely prevents the IDE CD-ROM module from grabbing hdX.
Using ide-scsi emulation for a particular IDE (actually ATAPI) device
does not allow a device to transcend the brain-damage built in to the
IDE bus. It lets a userspace program treat an ATAPI device as a SCSI
device.

--
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
Brainbench MVP for Linux Admin /
http://www.brainbench.com / "He is a rhythmic movement of the
-----------------------------/ penguins, is Tux." --MegaHAL

In article <slrnbiga29.rbp.danceswithcrows@samantha.crow202.d yndns.org>, Dances With Crows wrote:
>
> Badly, since IDE devices don't share the bus well at all. Copying
> things from /dev/hdc to /dev/hdd is much slower than copying things from
> /dev/hda to /dev/hdc . Put your disks on one channel and your
> CD/DVD devices on the other channel....

This is not a hard and fast rule. A lot depends on the OS, distro,
and even the bios/mb. I can't remember an example/exceptions with
Linux (although I have a niggling feeling I've encountered one), but
there's definitely some cases where is won't work. One example is
Unixware 8 which will not load unless the boot CD is on the primary
(slave). I've also run across this weirdness with w2K on one box.
Sometimes you just gotta play around till it works.

nb