Petter Reinholdtsen

Quicker Debian installations using eatmydata
25th November 2016

Two years ago, I did some experiments with eatmydata and the Debian installation system, observing how using eatmydata could speed up the installation quite a bit. My testing measured speedup around 20-40 percent for Debian Edu, where we install around 1000 packages from within the installer. The eatmydata package provide a way to disable/delay file system flushing. This is a bit risky in the general case, as files that should be stored on disk will stay only in memory a bit longer than expected, causing problems if a machine crashes at an inconvenient time. But for an installation, if the machine crashes during installation the process is normally restarted, and avoiding disk operations as much as possible to speed up the process make perfect sense.

I added code in the Debian Edu specific installation code to enable eatmydata, but did not have time to push it any further. But a few months ago I picked it up again and worked with the libeatmydata package maintainer Mattia Rizzolo to make it easier for everyone to get this installation speedup in Debian. Thanks to our cooperation There is now an eatmydata-udeb package in Debian testing and unstable, and simply enabling/installing it in debian-installer (d-i) is enough to get the quicker installations. It can be enabled using preseeding. The following untested kernel argument should do the trick:

preseed/early_command="anna-install eatmydata-udeb"

This should ask d-i to install the package inside the d-i environment early in the installation sequence. Having it installed in d-i in turn will make sure the relevant scripts are called just after debootstrap filled /target/ with the freshly installed Debian system to configure apt to run dpkg with eatmydata. This is enough to speed up the installation process. There is a proposal to extend the idea a bit further by using /etc/ instead of apt.conf, but I have not tested its impact.

Tags: debian, debian edu, english.

Created by Chronicle v4.6