Re: cd writers & linux
Paul Miller wrote:
>
> On Mon, 8 Jun 1998, Stephen Carpenter wrote:
>
> > They make permanant pits iinto the disk and can not be erased (well
ok...
> > they can be erased...just dip them in some acetone... but they can not
> > be erased AND re-used)
>
> After looking around on the net, I think that is right.
>
Yes. Although you can write multiple sessions to a CDR. If you have
space
at the end of a CDR, you can tack on more files later, but you can't
overwrite
anything you've written.
> hmmm... I think rewritable discs are magnetic and they can only be read
on
> other CD-RW drives or DVD drives.
>
Nope. There's no such thing as a magnetic CDROM/DVD. They use a
different
power laser, and require the same on anything that tries to read the CD-RW.
All newer CDROM/DVD will read CD-RW's (they will say they support
multi-read). In fact, I have a sony stereo that will play audio CD-RW's
(although most audio equipment won't play them).
> If the drive has a 1MB or 2MB buffer and is only writing at 2X or 4X, why
> does it matter how fast the interface is? Most drives are 2X, which is
> something like 300KB/s.. My motherboard supports up to 20MB/s on both of
> its IDE channels. So even if the drive is on a shared channel, it'll
> still be able to continously write at 300KB/s, right?
>
Speed is not an issue, reliability is. SCSI is MUCH more reliable that
IDE. I tried to copy a scratched CD on an IDE CDROM once. It got to a
damaged file, puked & died on the spot. I tried copying it from a SCSI
CDROM,
and it took about 30 seconds while it retried, but it copied the file and
continued on.
IDE does not deal well with errors during reading or writing. IDE
devices
tend to just give up, while SCSI does the best it can to continue. SCSI
also
uses less CPU time than even UDMA. This isn't a big deal if you are
exclusively using your machine as a burner, but I've done compiles, used
netscape, etc. while burning CDs under linux. I would not even think of
doing
that with an IDE burner.
I'm not saying you shouldn't get an IDE burner. It will probably work OK
and will cost much less, but SCSI is a better option if you can afford it.
Kerry
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Let me add my two cents worth:
SCSI is a multi-tasking interface, each device on the bus can be active at
the same time (at least each device can be issued commands while others are
running). IDE is single tasking. That's why the CD burner MUST be on its
own ide controler. With two ide controlers you can transfer from a hard
disk (ide0) to the CD burner (ide1). Used this way the ide cd burners (at
least up to 2x speed) should work well (but see comment below). I don't
know if the CDR drive makers are putting the same quality firmware into the
ide drives as they are into the SCSI drives. That could account for a
difference, not the interface used. Also there is SCSI and then there is
SCSI. What kind of host adapator you use makes a difference. A programed
IO SCSI interface card with a small buffer might be WORSE than an IDE
interface. I think that unless you have a 2940 or equalivant bus master
card you might not be any better off with SCSI than IDE. I have not gotten
a CDR drive yet (when the price drops below $200 I'll byte). I have a 2920
SCSI card in my computer, but its only driving a DCC tape drive so speed
here is not an issue. If I want to go SCSI for CDR I fear I'll have to
replace this with the 2940.
BTW people have told me that the biggest problem with CDR drives is heat.
They can't burn more than one CD without letting the drive cool down
inbetween and then only at 1X speed. The external drives work at 2X or 4X
but the internal ones I'm told get too hot at 2x and above to be reliable.
The fans inside the drive are just too small.
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