> On Mon, 27 Nov 2000, Bill Davidsen wrote:
>
> >> Direct CD is just an application. It writes to both CDR and CDRW
> >> using the UDF filesystem (packet writing). In the case of CDRW,
> >> this allows you to treat a CDRW as a big floppy disk. If you
> >> require this functionality, then you MUST use UDF under Linux,
> >> and it isn't a finished product. You need a 2.4.0 kernel and
> >> maybe some magic.
> >
> > Thank you for saving me the time to look up the correct terms for the
> >packet writing. I'm not sure about the degree of magic needed, the
> >2.4.0test10 config (last one I have here) shows:
> > # CONFIG_UDF_FS is not set
> > # CONFIG_UDF_RW is not set
> >so I am guessing that this stuff is now in the kernel at the bleeding
> >edge.
>
> Yep, thats right. It is not fully functional though, and write
> is marked DANGEROUS.
The whole development kernel series is dangerous if you ask me, so
that's relative ;-) The software RAID was dangerous for a year after I
started using it for production, and I still have 2.2.10 systems running
from June 1999 builds, because they haven't had a problem in all that
time to justify an outage.
I live a half mile east of a reactor, half mile west of an active
fault, under the landing pattern of a military airport. I can't get too
excited about these drivers.
More seriously, I certainly wouldn't use this code as my one and only
copy of something critical, but then I don't do that with ext2 and hard
drives either. I have heard good things about DVD-ROM, and if I could
solve the original problems with UFS I'd do it. However, that only
addresses part of the problem, but I'd still be using UFS to read data
if it were me.
> >It is not clear to me where the line falls between the physical (treat
> >the CDRW like a floppy) and the logical (UDF filesystem). I have a
> >distinct feeling that I've seen something about using other filesystems
> >with packet writing, but I have no idea why this might be desirable.
>
> CDR and CDRW media cannot be written to like magnetic media, so a
> filesystem like ext2 will not work R/W on CDRW.
Well CDR obviously can't, I'm not prepared to argue CDRW because it
would be too slow to be useful, but I thought packet mode could rewrite
sectors, but please don't take that as anything but a guess.
> Last time I checked, that wouldn't work under VMware. That was
> about 8 months ago though. If it does work now, you'd likely
> need a very fast system to prevent overruns on writes. I think
> it would still be quite risky. An idea though..
One of the "burn-proof" drives, maybe? I don't know how that would be
in this case.
> > This is a really interesting problem, and I can't tell you how glad I
> >am that it's not mine;-)
>
> I certainly agree there. ;o) I just use iso9660 and it works
> fine. It's really no less convenient to me.. One can do
> multisession until a disk is full, then copy to hd, blank,
> remaster, and go again. Not much more difficult than UDF IMHO.
>
> The convenience of UDF IMHO is outweighed by the loss of 150Mb of
> disk space... on DVD-RAM however... ;o)
I used to use xiafs on floppy and ZIP because it was less overhead. I
certainly agree that ~25% is a no-go for many uses.
--
-bill davidsen ([EMAIL PROTECTED])
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
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