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debian-cd BoF at DebConf

[ Please note the cross-post and Reply-To ]

Hi folks,

Here's a summary of what we discussed in the debian-cd BoF [1] last
week (9th July). Thanks to the awesome efforts of the DebConf video
team, the video of the session is already online [2] in case you
missed it. I've also attached the Gobby notes that were taken during
the session. Again, thanks to the people who took part - we had a very
useful discussion.

CD sizing problems

As already mentioned in a few places, we're currently struggling to
fit the large desktop tasks onto the respective versions of
CD#1. There's been a lot of discussion about this, and some work done
to try and solve the problem. Joey Hess and I spent some time together
during DebCamp working on tasks and that's helped, but not enough to
fix the problem entirely.

There has been much discussion about switching packages over to using
xz compression instead of gzip by default, including Hideki Yamane's
excellent session "Let's shrink Debian package archive!" [3]. Ansgar
has been looking into the possibilities here of re-building a subset
of the core packages using xz, and I think it's clear that this is the
solution for Wheezy at least. In discussion after Hideki's xz talk, I
think there was broad agreement that we should just switch to xz by
default, *but* with the option to use a different (or even null)
compressor where it makes sense (e.g. in packages full of
already-compressed files such as open-clipart). There has been a
suggestion that we should leave base packages using gzip for the sake
of foreign users of debootstrap, but I firmly believe we should just
tell them they'll need xz in future. Let's not hold ourself back

In the longer term, even xz is not going to solve the problem of
making CD#1 viable alone for installing the large desktops. There are
a few options for that:

 * Stop promising that we can supply a good desktop using just CD#1 -
   tell people they'll need more than one CD - add more CDs, or a DVD
   or network...

 * Make the first "CD" image bigger, such that it's not going to fit
   on CD any more. debian-live and Ubuntu have already done this. This
   might sound silly, but we've got more and more people using
   isohybrid images on USB sticks already. We could provide 1GB or 2GB
   images specifically optimised for these users. Side point: in the
   the existing DVD sets for amd64 and i386, we already limit the size
   of the first DVD image to 4GB so that it's useful on 4GB USB
   sticks. If people want 1GB or 2GB stick images, let us know! We're
   not going to provide all possible sizes, of course...

 * Give up on normal-size CD images altogether. Use the netinst for
   small downloads, otherwise use DVDs or bigger. We know that there
   are some people who still want CD sets (unable to use DVDs on older
   hardware?), but little idea of how many. CD sets are more expensive
   than DVDs (blank discs of each type are similarly priced) and much
   less convenient (disc swapping).

 * Switch to xfce / lxde by default on CD#1, leaving KDE/Gnome for
   larger sets / DVD / network installations.

One things that's obvious from the discussion: we don't have good
statistics to know exactly what solutions people are currently using
for installation. We don't have access to mirror download numbers. No
idea of how many times a given CD/USB stick may be used for
installation, nor what other apt sources might be used in parallel. A
wider usage survey would be good here - volunteers please!?! :-) Maybe
scope for extra info in popcon?

Too many CDs being produced

Again, this is a perennial problem. The current weekly CD sets are
getting huge: 73 CDs or 11 DVDs for amd64 alone! We've already trimmed
the sets produced such that for most architectures we only have a
small number of ISO images available for direct download and the rest
as only jigdo. Thus far, we've always produced *all* the ISOs for CD
and DVD for amd64, i386 and source. It's time to reduce that set:

 * 8 CD ISOs for amd64 and i386, none for source
 * 3 DVD ISOs for amd64 and i386; all the DVD ISOs for source

The reasoning for the source images is simple - we don't want to make
it harder for people to download our sources, but it's not so critical
to make them available on CD rather than DVD. We'll still continue to
make all images available in jigdo format: people can still make their
own 60+ mips CD set if they really want to, but we're not going to hit
the mirrors for this. We'll continue to 

We also currently produce netinst and businesscard "small" CDs for
most architectures at the moment (all except s390/x). The netinst
images work very well and seem to be the preferred installation option
for many (and now the default image linked from the front page of
www.d.o is the multi-arch amd64/i386 netinst). The businesscard images
don't have many users as far as we can tell, and they're quite
fragile, prone to breakage whenever the archive changes. For this
reason, we've stopped making the businesscard images; this got a lot
of backing at the BoF.

Finally, a requested "image" is a netinst-alike that would do the
barest minimum of installation questions etc., requiring no other
sources at all (so not even looking for security updates). Install
openssh-server automatically and then let people get straight in to
the system over the network for further configuration later. Not sure
if something like this might already be available using boot arguments
on the standard netinst CD - *tips appreciated here*.

EFI and Secure Boot

Just a brief mention here - there was a separate BoF about this and
I'll summarise that shortly. I think it's much too late in the release
process to get Secure Boot working for Wheezy, but we *do* need to get
EFI working. (Bug#658352). This should be do-able, but we'll need to
get lots of help with testing. I currently don't have any EFI-capable
machines at all, so need to fix that for simple development/testing
purposes anyway. Maybe worth asking the DPL for some Debian money to
acquire some machines for this. There will be a call for testing once
we have some stuff done.

(Real) multi-arch coming

debian-cd already produces so-called "multi-arch" CDs, but this is a
different concept to what "multi-arch" means elsewhere in Debian
now. In debian-cd, this means including equivalent installer and
packages for multiple architectures on one CD (or set of CDs). Support
for the more general multi-arch stuff will be more work (e.g. amd64
DVDs containing a partial archive of i386: versions of ia32-libs
packages). May not happen for wheezy without help; if it does, will
need help testing!

debian-live builds on debian.org machines

Daniel has been producing debian-live images for a long time on his
own machines, and that's worked well so long as he has the time to do
it. We've been discussing moving official builds onto the same machine
we use for building installer CDs (pettersson). Work is ongoing,
hopefully more news soon.

Summary (TL;DR)

Lots of work is ongoing in the CD space, with a fair bit still to do
before Wheezy... \o/ If you have any comments, questions, etc. then
please reply and let us know. Offers of help always appreciated!

[1] http://penta.debconf.org/dc12_schedule/events/871.en.html
[2] http://meetings-archive.debian.net/pub/debian-meetings/2012/debconf12/high/871_Debian-CD.ogv
[3] http://penta.debconf.org/dc12_schedule/events/930.en.html

Steve McIntyre, Cambridge, UK.                                steve@einval.com
"Managing a volunteer open source project is a lot like herding
 kittens, except the kittens randomly appear and disappear because they
 have day jobs." -- Matt Mackall
Please take notes here
  xz compression better than gzip by ~20%.
  Release goal to use xz.
Sizing problems *again*
 * multiple CDs needed? maybe
   73 CD's for Wheezy. 11 DVD's.
   for main i386, amd64 & source - provide every ISO.
   other architectures are only jigdo after the first 3.
Many MANY CDs - what should we do?
   reduced set of ISO images. Continue distributing source on DVD.
EFI (& secure boot)
   help needed to test and fix EFI.
   - hardware for testing
(real) multi-arch coming
   multi-arch in debian-cd differed. amd64 & i386 on one image for native use.
   MultiArch itself is confusing as a duplicated name. Beyond Wheezy partial 
   architectures may be used. Difficult to test, need volunteers.
live builds on pettersson, coming soon!
   Debian Live builds to happen on the same machine, regularly built.

Of the existing users, how many use CD#1? small %.
How many people only burn a single CD without network access? Unknown.

One option is to make the first 'cd' too big for a real CDR anymore.
USB the primary medium?

First DVD in the set is limited down to 4Gb for a USB stick.
KDE and GNOME could be managed with 1Gb or maybe 2Gb USB sticks.

Is a LiveCD a better option for some people who want to still use CDR?
Create a wider survey on usage and expectations.
Download statistics are missing. % are available from some mirrors and
usage of an individual download could be installed any number of times.

If we could add installation method into popcon, some of that data could be

The build done on Tuesday 10th July for Wheezy AMD64 comes up to 73 CDs. It is 
not likely for somebody to download all of these CD images. Thus, for Wheezy, a 
reduced set of ISO images is proposed.
netinst to get a cold machine to be booted and running SSH. Preference would
be to have a standalone object which needs no networking and without needing
to install other updates of packages which may not be required.

Backing to drop businesscard images.

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