How to install NixOS from NixOS
When the last semester came to an end, I noticed that my Thinkpad behaved weird.
nix-store --optimize it, and some other things began to fail
I suspected the SSD was dying, a Crucial C400 with 256GB.
So I ran the
smart tools with a short test – But it told me everything was
Then I ran the extended self-test on the drive and after 40% of the check (60%
remaining) it told me about dead sectors, nonrecoverable.
So I got a new SSD and installed NixOS from my old installation. Here's how.
So I got a nice new Samsung EVO 850 PRO with 256 GB. I was really amazed how light these things are today. No heavy metal in there like in a HDD!
First of, you need to prepare your current installation. Make some backups, be sure everything is fine with them.
Then, verify that your
configuration.nix and your
file list your partitions not by UUID, but by
/dev/sda1 and so on.
That could be really helpful later.
If you have some crypto keys you need to keep, maybe make another backup of them.
First of, we need to format the new drive.
gdisk for this if you have a UEFI setup like with an Thinkpad X220.
Format your partitions after that.
Make sure that your boot partition is formatted as
I don't know why, but it is only possible to boot from
according to the nixos documentation.
Also, do your
For simplicity, I refer to the boot partition by
/dev/sda1 and to the
root/home partition as
/dev/sda2 – you can, of course, have more partitions,
maybe for a seperate
But I saw no need for it.
With only one partition I do not have to take care of the size of the
/nix/store and if I have few things in the store I can grow my music
collection a bit – so I'm really flexible.
And yes, I know about LVM, but I really don't need these things, do I?
Now, mount the partitions as follows:
/mnt/boot(you might need to
mkdirthis directory first)
Ensure things are properly mounted.
This broke my neck twice during my installation, as
/mnt/boot wasn't mounted
properly and I failed to rebuild the system.
Took me some time to see this, actually.
Now you can
nixos-generate-config --root /mnt.
After that you might want to modify your
configuration.nix file in the newly
generated setup under
/mnt/etc/nixos/configuration.nix – I did not!
nixos-install --root /mnted to get a minimal bootable system.
rsync -aed my
/mnt/home/ and symlinked the
configuration.nix (which lives in
my machines) to
I renamed the host as well, to avoid confusion.
shutdowned, removed the old SSD, assembled the new one and booted.
I had some problems with failing mounts during boot (because I had mount
operations specified by UUID rather than via
I got a rescue shell and was able to fix things up.
After several reboots I was able to get my system up and running.
When I was able to boot my minimal installation, I just followed
and created my user and so on.
And because I copied my whole
configuration.nix setup from my old drive,
everything got build for me.
After some more
nix-env -iA calls (because some things only live in my user
environment), I fully restored my system.
Installing NixOS from NixOS works really nice. You have to be careful with some things, UUIDs and so on, but overall it is rather simple.
Anyways, you benefit if you really know your system. I wouldn't necessarily recommend this to an inexperienced NixOS user – hacking things into the TTYs and getting a rescue shell for fixing the installation is no thing that a newbie really wants to do – except for learing and if backups are at hand!
Because of the awesomeness of NixOS and the
configuration.nix file, I was able
to rebuild my complete system within a few minutes.
Despite my extensive adaptions in my
configuration.nix file – speaking of
container setup, custom compile flags for packages, custom vim setup with
plugins compiled into the vim derivation (and the same again for neovim),
hundreds of packages and stuff – I was able to rebuild my system without much
Overall, leaving out the UUID fail, I think I am able to redo a complete setup
/home, which was ~100GB data, and reinstalling everything)
in maybe 90 minutes, depending on how fast the internet connection is for
One could even mount the old
/nix/store from the old installation and copy
over derivations, which would be a hell lot faster and would result in a
reinstallation without the need for internet access.
But I don't know how to do it, so I leave it as exercise to the reader.