Re: linux kernel error reading end of cd/dvd
On Wed, Oct 15, 2003 at 12:33:12AM +1300, Volker Kuhlmann wrote:
> > If we're talking about ISO9660 layout prepared by mkisofs,
> > then those "more blocks" are known to be insignificant and
> > you can as well checksum every file instead of the whole
> > filesystem image, can't you?
>
> No. Checksumming only files does not checksum (all of)
> the filesystem's metadata. From an efficiency viewpoint,
> checksumming files is out of the question. Checksumming the
> disk is very fast, and independent of the filesystem used. In
> the case of iso9660, checksumming files may be slower by
> only a factor of two (sorry can't remember right now), for
> udf and ext2 you can plain forget about it from a practical
> perspective. The only fast way of doing it would be to read
> the whole CD/DVD image to disk, loopmount, check files - might
> check the disk itself in the first place.
>
> > Does it really have to be whole image?
>
> Yes. And it *ought* to work ;)
(From someone who doesn't know much about CD's)
I used to checksum all the files (after finding that
checksumming the whole disk doesn't work -- something beyond
my understanding). This stopped abruptly after I upgraded my
Linux kernel to 2.4, when mounting a hfs disk started to crash
the kernel. I had to simply give people disks that I could not
verify as having been written correctly.
So if I might add something to the "efficiency" argument, I
might add that for me to checksum my disk, I'll need to checksum
all the files twice (once for iso9660, once for hfs), and all
this is provided that checksumming all the files would actually
work (which is not the case right now).
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