Storage optimization: Difference between revisions

Line 144:

This is easiest to set up while installing NixOS, but <code>/nix</code> can be moved on a live system:

~~# Create a new partition and mount it over <code>/mnt</code>~~

''All commands below are executed with root privileges''

~~# <code>rsync -aAxv</code> everything from <code>/nix</code> to <code>/mnt</code>~~

~~# Bind <code>/mnt</code> to <code>/nix</code> (e.g. using <code>mount</code>).~~

~~# Restart nix daemon~~ with ~~<code>systemctl restart nix-daemon.service </code> <code>systemctl restart nix-daemon.socket </code>.~~

# Rerun <code>nixos-rebuild switch</code> with something like <syntaxhighlight lang="bash">fileSystems."/nix" = { device = "/dev/disk/by-label/nix"; neededForBoot = true; options = [ "noatime" ]; };</syntaxhighlight>

# Reboot to be sure <code>/nix/store</code> is properly mounted.

# Create a new partition

# Once you are sure everything works, you can delete the old store ~~doing a bind mount~~ <~~code~~>/</~~code> to <code>~~/old_root</~~code>, and remove <code>~~/old_root/nix</~~code~~>.

# Mount this new partition over <code>/mnt</code> <syntaxhighlight lang="bash">

mount /dev/disk/by-label/nix /mnt

</syntaxhighlight>

# Copy everything from <code>/nix</code> to <code>/mnt</code> ''Trailing slash are important'' <syntaxhighlight lang="bash">

rsync --archive --acls --one-file-system --verbose /nix/store/ /mnt/store

rsync --archive --acls --one-file-system --verbose /nix/var/ /mnt/var

</syntaxhighlight>

# Use the new partition as new <code>/nix</code> <syntaxhighlight lang="bash">

umount /mnt

mount /dev/disk/by-label/nix /nix

</syntaxhighlight>

# Restart nix daemon <syntaxhighlight lang="bash">

systemctl stop nix-daemon.service

systemctl restart nix-daemon.socket

systemctl start nix-daemon.service

</syntaxhighlight>

# Add mounting the <code>/nix</code> partition to your <code>/etc/nixos/configuration.nix</code> <syntaxhighlight lang="nix">

{

# ...

fileSystems."/nix" = {

device = "/dev/disk/by-label/nix";

fsType = "ext4";

neededForBoot = true;

options = [ "noatime" ];

};

# ...

}

</syntaxhighlight>

# Apply your configuration <syntaxhighlight lang="bash">

nixos-rebuild switch

</syntaxhighlight>

# Reboot to be sure <code>/nix/store</code> is properly mounted

# After reboot, check that <code>/nix</code> is mounted over your partition <syntaxhighlight lang="bash">

mount | grep "/nix" && echo "Nix seems to use your new partition" || echo "It seems that something bad happened"

</syntaxhighlight>

# Once '''you are sure''' everything works, you can delete the old store <syntaxhighlight lang="bash">

mkdir /tmp/old_root

mount --bind / /tmp/old_root

rm --recursive /tmp/old_root/nix

umount /tmp/old_root

rmdir /tmp/old_root

</syntaxhighlight>

Keep in mind that all commands like <code>mount</code> and <code>bash</code> point to some executable in <code>/nix/store</code>, so never mount an empty disk over <code>/nix</code> or <code>/nix/store</code>, otherwise you will be locked out until reboot!

@@ Line 144: / Line 144: @@
 This is easiest to set up while installing NixOS, but <code>/nix</code> can be moved on a live system:
-# Create a new partition and mount it over <code>/mnt</code>
+''All commands below are executed with root privileges''
-# <code>rsync -aAxv</code> everything from <code>/nix</code> to <code>/mnt</code>
-# Bind <code>/mnt</code> to <code>/nix</code> (e.g. using <code>mount</code>).
-# Restart nix daemon with <code>systemctl restart nix-daemon.service </code> <code>systemctl restart nix-daemon.socket </code>.
-# Rerun <code>nixos-rebuild switch</code> with something like <syntaxhighlight lang="bash">fileSystems."/nix" = { device = "/dev/disk/by-label/nix";  neededForBoot = true; options = [ "noatime" ]; };</syntaxhighlight>
-# Reboot to be sure <code>/nix/store</code> is properly mounted.
+# Create a new partition
-# Once you are sure everything works, you can delete the old store doing a bind mount <code>/</code> to <code>/old_root</code>, and remove <code>/old_root/nix</code>.
+# Mount this new partition over <code>/mnt</code> <syntaxhighlight lang="bash">
+mount /dev/disk/by-label/nix /mnt
+</syntaxhighlight>
+# Copy everything from <code>/nix</code> to <code>/mnt</code> ''Trailing slash are important'' <syntaxhighlight lang="bash">
+rsync --archive --acls --one-file-system --verbose /nix/store/ /mnt/store
+rsync --archive --acls --one-file-system --verbose /nix/var/ /mnt/var
+</syntaxhighlight>
+# Use the new partition as new <code>/nix</code> <syntaxhighlight lang="bash">
+umount /mnt
+mount /dev/disk/by-label/nix /nix
+</syntaxhighlight>
+# Restart nix daemon <syntaxhighlight lang="bash">
+systemctl stop nix-daemon.service
+systemctl restart nix-daemon.socket
+systemctl start nix-daemon.service
+</syntaxhighlight>
+# Add mounting the <code>/nix</code> partition to your <code>/etc/nixos/configuration.nix</code> <syntaxhighlight lang="nix">
+{
+   # ...
+   fileSystems."/nix" = {
+     device = "/dev/disk/by-label/nix";
+     fsType = "ext4";
+     neededForBoot = true;
+     options = [ "noatime" ];
+   };
+   # ...
+}
+</syntaxhighlight>
+# Apply your configuration <syntaxhighlight lang="bash">
+nixos-rebuild switch
+</syntaxhighlight>
+# Reboot to be sure <code>/nix/store</code> is properly mounted
+# After reboot, check that <code>/nix</code> is mounted over your partition <syntaxhighlight lang="bash">
+mount | grep "/nix" && echo "Nix seems to use your new partition" || echo "It seems that something bad happened"
+</syntaxhighlight>
+# Once '''you are sure''' everything works, you can delete the old store <syntaxhighlight lang="bash">
+mkdir /tmp/old_root
+mount --bind / /tmp/old_root
+rm --recursive /tmp/old_root/nix
+umount /tmp/old_root
+rmdir /tmp/old_root
+</syntaxhighlight>
 Keep in mind that all commands like <code>mount</code> and <code>bash</code> point to some executable in <code>/nix/store</code>, so never mount an empty disk over <code>/nix</code> or <code>/nix/store</code>, otherwise you will be locked out until reboot!