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Some bits of experience gained from handling upgrade-reports.



Hello Debian developers,

[Please store this mail in a safe place and read it when you have
recovered from the release party.]

During the few weeks before sarge release, I have tried to reproduce the
upgrade problems reported to upgrade-reports [1]. I reached the following
conclusions:

1) Circular dependencies are cause of lot of breakage. Worse, the
problem that plague the woody to sarge upgrade are not circular
dependency in sarge but in woody. It means that if we want a nice etch
to etch+1 transition, we need to try to get rid of them now.
Usually it can be achieved by spliting packages to isolate the
dependency.

2) apt and aptitude reliance on C++ make them quite painful to upgrade
before doing the dist-upgrade due to C++ ABI changes. This issue is
likely to be the same during the sarge to etch upgrade, so we should not
rely on the user installing the latest apt or aptitude version before 
upgrading.

3) There are far too many packages that mess with conffiles causing
useless dpkg conffiles handling. We should strive to do better in etch.
Never move a conffile in a maintainer script without checking the md5sum
against the stable version of the conffile. If it match, remove it
instead instead of moving it. It is the same if you use ucf instead.

4) Upgrade-test need to be done continuously because there is not enough
time during the freeze to fix all the problems. Another conclusion is
that this need to be done automatically. This could be done roughly
the same way as a buildd work, but would generate a 'upgrade
certificate' instead of a package. Such test will also find the 
packages that cannot be installed due to maintainers scripts breakage.

Unfortunately I do not have access to suitable hardware anymore to do
such upgrade test, so help with this project would be more than
welcome. Some kind of virtualisation technology like user-mode-linux
might be required (that is what I was using).

As a conclusion, I am not very happy with the state of woody to sarge
upgrade. I expect around 30% of users will suffer serious breakage that 
could have been avoided. This statistic assume smart users. We should do
better for etch.

Acknowledgement:
----------------
I would like to thanks Frans Pop and Steve Langasek for bearing with me
while I was inflating the release notes changes and the RC bugs count and
for generally be helpful at trying to solve upgrade issue.

I would also like to thanks people that took the trouble to send
upgrade-reports.

Cheers,
-- 
Bill. <ballombe@debian.org>

Imagine a large red swirl here. 

[1] <http://bugs.debian.org/upgrade-reports>

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