I know I can't install previous version without a local copy of the archive of needed version. But today I found out something surprising: I was sure that all previous archives are stored in cache. But after I upgraded firefox from v28 to v29 and checked available versions to install, result is unexpected for me:
$ apt-cache madison firefox firefox | 29.0+build1-0ubuntu0.12.04.2 | http://archive.ubuntu.com/ubuntu/ precise-updates/main i386 Packages firefox | 29.0+build1-0ubuntu0.12.04.2 | http://security.ubuntu.com/ubuntu/ precise-security/main i386 Packages firefox | 11.0+build1-0ubuntu4 | http://archive.ubuntu.com/ubuntu/ precise/main i386 Packages
There is no version 28. I checked
/var/cache/apt/archives, and there is actually no archive of version 28. That is sad that it is removed.
How can I prevent it from removing old archives?