Separate downloading and upgrading

[Marius Gedminas]

Currently the distribution upgrade is monolithic: after the confirmation it downloads all the packages and starts upgrading them immediately. That doesn't suit me much: the download time is not predictable (and can take several hours on a slow connection, or on a fast connection, when the mirrors are overloaded). I wish to continue working normally while update manager downloads the packages. Then I wish to choose the time when update manager starts the upgrade (what if it upgrades some package when I'm in the middle of using it?).

Previously I used to change /etc/apt/sources to the next release and run apt-get-update; apt-get dist-upgrade -d to download most of the packages into /var/cache/apt/archives. Later I'd run update-manager to do the upgrade and most of the packages would already be downloaded.

I tried the same yesterday. I spent the whole day downloading debs at 20 kilobytes/second. Today I ran update-manager and it said that it needed to download > 900 megs. I check /var/cache/apt/archives, and it's mostly empty. I do not know which piece of code ran apt-get clean, but it certainly wasn't I.

My request for this bug report: please allow the user to choose to download the packages only and install them at a latter time. Or, at the very least, do not clean the apt cache before downloading the packages.