Re: Indexes of DVD 2,3,... on DVD1?
On Sat, Jun 07, 2025 at 12:25:14PM +0900, Simon Richter wrote:
> Hi,
>
> On 06.06.25 06:38, Andrew M.A. Cater wrote:
>
> > If you're doing this offline, then you probably ought to also be generating
> > the other DVD images anyway to take with you to your desert island in
> > order to prove that Debian's desert island test remains valid.
>
> Yes, the problem isn't so much "having the media" as "having to swap the
> media." The solution proposed by the question asker is wrong, but the proper
> solution would require support during image generation.
>
> Right now, if you have all 50 or so DVDs, a fully offline installation
> requires you to present all of them to the installer, in turn, before
> installation starts, so 50 disc changes. Then, if you do a default
> installation, you only need disc 1, and feel a bit silly for doing the
> entire dance before.
>
At this point, I'd probably use the Blu-Ray disks or even the dlbd
double layer Blu-Ray**
** The usefulness of these in general is fairly small though the numbers
of users still using these is unknown. Almost certainly at this point,
nobody still uses these on real, expensive physical media rather than
copying them to a USB stick. The Debian images and install media team
may eventually further rationalise the numbers of images and jigdo files
released at each point release.
> Problem is, there is also no way for the user to know which discs are needed
> before package selection, and the person asking the question had
> installations fail because they assumed they could get away with only adding
> the first three discs, but on that particular machine, a package from a
> later disc was required. We don't give out guidance like "if you need xfce,
> you also need disc 3 and 4", for good reasons, but it means that airgapped
> installations are very cumbersome.
>
With the varying sizes of packages with every release and the fact that
packages are assigned to media by approximate popularity and size to fit
a disk image, this is almost unknowable in advance unless you grep the
installed files list. It's a particular struggle to maintain the netinst
at a reasonable size as it is for DVD 1. [DVD 1 is limited to 4GB to allow
the image to be written to a 4GB USB stick, even though it's almost
impossible to find a 4GB USB stick this small these days].
> So if disc 1 also had the indexes available for the other discs, we could
> simply ask "which installer discs do you have available?" (comma separated
> list of ranges), add their indexes from that prompt, and then ask only for
> the required ones during installation. The user will still need to prepare
> all of them if they need the guarantee that they will be able to complete an
> installation, but at least the number of disc swaps will be greatly reduced.
>
Agreed but this would also need changes in the installer logic. For the
very limited use case, the pain and problems probably outweigh the disk
space problems on each medium and the complexity of the change required.
If you *really* want the desert island install, it's almost easier to
take a netinst medium and a laptop/small machine with a full Debian mirror
In order to save space on Debian CD mirror machines worldwide, the images
beyond DVD3 and equivalents have been reduced to corresponding .jigdo
files and templates so you really need a mirror to create the media for
an offline install anyway.
The size/number of images (and the complexity of maintaining the archive)
versus diminishing returns in effort is something we often mention in
passing within the images team while chatting amongst ourselves as we are
testing installs and preparing point releases. It is absolutely
true that some images have never been tested over a period of years
as noted in the testing matrix for each point release.
> Simon
All the very best, as ever,
Andy Cater
(amacater@debian.org)
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