Re: Content of CDs / DVDs
On Thu, Oct 21, 2004 at 02:28:27PM +0100, Steve McIntyre wrote:
> Richard Atterer writes:
> >(Of course, at the expense of outputting images with a wrong (i.e. zero)
> >image md5sum, you can go faster...)
>
> Yes. I was discussing this with some people last night. The MD5 step
> is the hard bit. If we are prepared to lose the MD5 of the entire
> image (or use another checksum algorithm that can be updated just
> using existing checksums of the parts in the image) then we could
> probably generate jigdo files on the fly in _seconds_ simply by using
> the data already in the Packages files. We'd need to make a few tweaks
> to the CD layout, but it's doable if we want it.
I'm not sure if it's worth it to switch to another type of checksum: The
template data already has checksums for the individual files, and the
remaining compressed data in the template is protected by the compression's
checksum.
(An RsyncSum64 would fit your description; if you have the checksum for two
chunks of data, then calculating the checksum for the concatenated data is
very cheap.)
I think that ATM jigdo does not recognize a zero md5sum as special, it'll
report a checksum mismatch. Should I change that?
IMHO official images should include a valid image md5sum, though.
Cheers,
Richard
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