As the title says, how long does a distribution upgrade (e.g. from 11.04 to 11.10) usually take, discounting the download phase? I've been upgrading from Natty to Oneiric, the download only takes about 1 hour, but now I've been in the "Installing the upgrades" phase for more than 5 hours already. The progress bar has been stuck saying "About 2 hours 55 minutes remaining" in the last 3 hours, and the remaining time is not decreasing. The detailed view (Terminal view) still scrolls printing stuffs that it's installing, so the upgrade is still running, albeit ever so slowly.

In short, is it normal that the Ubuntu upgrade takes this long? Fresh install, as I remember, takes about an hour or so from inserting the CD to booting to the harddisk; I had expected that an upgrade may take longer than fresh install, but not by this much.

Second question, why does it take so long to upgrade vs fresh install? Certainly not the download time, since that takes about the same time, about an hour for both fresh install and upgrade. It's the installation phase that takes so long.

The upgrade finally finished a couple of hours after I posted, I'm still not sure why it takes so long; however when debugging another (possibly) unrelated performance problem in my program (running on this same laptop), I found out that SQLite is excruciatingly slow on ext4 (in my case, a 10 second operation turns to 5 minute), because ext4 enabled write-barrier by default. The root of the slow upgrade might be the same since distribution upgrade also involves a lot of disk writes.