Re: Non-RW media; WORM hopes

On 2007.06.12 23:07, RB wrote:
> On 6/12/07, Phillip Susi <[email protected]> wrote:
> > The media must be formatted for packet writing mode and you must=20
> use
> a
> > block size equal to the packet size ( 32k by default ).
>=20
> I wish I weren't so dense.  I thought the default packet size for
> optical media was 2k - where do you get 32k?
>=20
> Regardless, I can't get any of the UDF formatting tools to do=20
> anything
> anyway 'mkudffs -r 0x0150 --media-type=3Dworm /dev/hdc 359845' fails
> silently with EROFS and EBADF; 'cdrwtool -d /dev/hdd -u 359845' runs=20
> a
> bit, then fails with 'bad sector' IDE errors.
>=20
> Is the comment about formatting the media an esoteric one or do you
> know something about one of the tools I'm unaware of?
> --=20
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>=20


RB,

The packet/block size on CDs is indeed 2k. On DVDs, its 32kB, however,=20
the logical block size is faked by the drive to be 2k to get standards=20
compliance. That means a DVD drive does read/modifiy/writes 16 times=20
for every 2k packet you write. This reuslts in a huge slowdown. Writing=20
32kB blocks is much faster.

For CD-RW media you must format the media before your mount it. A=20
format involves writing the entire surface of the disk.

I haven't tried DVD-RW media.=20

With DVD+RW media, packet writing is not required. DVD+RW supports=20
proper random access and can support the filesystem of your choice.
However, UDF is still a good choice. With the limited write life of DVD
+RW, journaling and defualt -o rw mounts must be avoided.

Its all at http://fy.chalmers.se/~appro/linux/DVD+RW/

Regards,

Roy Bamford