Storage optimization: Difference between revisions
imported>Makefu initial batch of nixos-users |
imported>Fadenb m Syntax highlighting |
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If your root device is fixed and small-sized, you should move <code>/nix</code> to separate device. I have it running on LVM. Best to design that out of starts, otherwise you have to: - first you should know, that commands <code>mount</code> and <code>bash</code> belong to <code>/nix/store</code> so never mount empty disk over <code>/nix</code> or <code>/nix/store</code>, you will be locked out until reboot - create new ext4 FS and mount it over <code>/mnt</code> - <code>rsync -a</code> everything from <code>/nix</code> to <code>/mnt</code> - bind mount <code>/mnt</code> over <code>/nix</code> and rerun <code>nixos-rebuild switch</code> with something like | If your root device is fixed and small-sized, you should move <code>/nix</code> to separate device. I have it running on LVM. Best to design that out of starts, otherwise you have to: - first you should know, that commands <code>mount</code> and <code>bash</code> belong to <code>/nix/store</code> so never mount empty disk over <code>/nix</code> or <code>/nix/store</code>, you will be locked out until reboot - create new ext4 FS and mount it over <code>/mnt</code> - <code>rsync -a</code> everything from <code>/nix</code> to <code>/mnt</code> - bind mount <code>/mnt</code> over <code>/nix</code> and rerun <code>nixos-rebuild switch</code> with something like | ||
< | <syntaxhighlight lang="bash">fileSystems."/nix" = { device = "/dev/disk/by-label/nix"; options = [ "noatime" ]; };</syntaxhighlight> | ||
* reboot to be sure <code>/nix/store</code> is properly mounted | * reboot to be sure <code>/nix/store</code> is properly mounted | ||
* bind mount <code>/</code> to <code>/old_root</code>, and remove <code>/old_root/nix</code> | * bind mount <code>/</code> to <code>/old_root</code>, and remove <code>/old_root/nix</code> | ||
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Next you may enable periodic auto GC, like this: | Next you may enable periodic auto GC, like this: | ||
< | <syntaxhighlight lang="bash"> | ||
nix.gc.automatic = true; | |||
nix.gc.dates = "weekly"; | |||
nix.gc.options = "--delete-older-than 30d";</syntaxhighlight> | |||
In my case this results into some redownloads (if you ever use <code>import (builtins.fetchFromTarball ...)</code> all these fetched tarballs are not referenced anywhere and removed on GC), but overall it frees you from runnning GC manually often. | In my case this results into some redownloads (if you ever use <code>import (builtins.fetchFromTarball ...)</code> all these fetched tarballs are not referenced anywhere and removed on GC), but overall it frees you from runnning GC manually often. | ||
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One of least mentioned problems with <code>nix-collect-garbage -d</code> is it doesn't collect all the garbage! The key to understand how's that, is to run command: | One of least mentioned problems with <code>nix-collect-garbage -d</code> is it doesn't collect all the garbage! The key to understand how's that, is to run command: | ||
< | <syntaxhighlight lang="bash">$ nix-store --gc --print-roots | ||
/home/danbst/dev/test-shell/.shell.drv - | /home/danbst/dev/test-shell/.shell.drv -> /nix/store/4diqwczyjipdqyi7aj34wfagblbhfjr9-nixops-1.4 | ||
/home/danbst/dev/test-shell/.shell.drv-2 - | /home/danbst/dev/test-shell/.shell.drv-2 -> /nix/store/62h3c4d6rdnlxichixqg8h9jxi8nhxk0-stdenv | ||
/home/danbst/dev/test-shell/.shell.drv-2-doc - | /home/danbst/dev/test-shell/.shell.drv-2-doc -> /nix/store/14gnv1q1w0n9qwa3q23idsqvn51354y8-bash-4.3-p42-doc | ||
/home/danbst/stack/new/website/server/result - | /home/danbst/stack/new/website/server/result -> /nix/store/1jhmp6vl364p32r8bjigk65qh1xa562f-server-0.1.0.0 | ||
/home/danbst/testing/.nix-gc-roots/shell.drv - | /home/danbst/testing/.nix-gc-roots/shell.drv -> /nix/store/v3vqf48awjjzjivrx15kfqdh1d7cg4mq-sshpass-1.05 | ||
... | ... | ||
/home/danbst/testing/.nix-gc-roots/shell.drv-12 - | /home/danbst/testing/.nix-gc-roots/shell.drv-12 -> /nix/store/a2li4sl9pxh9aflqia2gp7w88ayvjwci-bash-4.3-p42 | ||
/home/danbst/testing/.nix-gc-roots/shell.drv-12-doc - | /home/danbst/testing/.nix-gc-roots/shell.drv-12-doc -> /nix/store/kcswyb1d8zimkym0pjfi2fj1dly1w34w-bash-4.3-p42-doc | ||
/home/danbst/testing/.nix-gc-roots/shell.drv-12-info - | /home/danbst/testing/.nix-gc-roots/shell.drv-12-info -> /nix/store/njb817fwiafswzwvj9skw7w7k6b3fnbi-bash-4.3-p42-info | ||
/home/ec2-user/result - | /home/ec2-user/result -> /nix/store/q35aq2sh5dbyka6g6f6qb7b8msxwds5m-nixos-system-iron-16.03.1299.a8e0739 | ||
/nix/var/nix/profiles/per-container/analyt/system-3-link - | /nix/var/nix/profiles/per-container/analyt/system-3-link -> /nix/store/snrj72189wh9va23fawl3v80v92xnxlm-nixos-system-iron-16.03.1291.efe2d64 | ||
/nix/var/nix/profiles/per-container/d-live/system-6-link - | /nix/var/nix/profiles/per-container/d-live/system-6-link -> /nix/store/cp2c58hnczsjk5h69ksajq5xfhsyhl6v-nixos-system-iron-16.03.1299.a8e0739 | ||
/nix/var/nix/profiles/per-container/d-test/system-4-link - | /nix/var/nix/profiles/per-container/d-test/system-4-link -> /nix/store/n1w7ywjg65x8iimchznxcyygbgmyfh55-nixos-system-iron-16.03.1287.6ac7ffd | ||
/nix/var/nix/profiles/per-container/dashboard/system-41-link - | /nix/var/nix/profiles/per-container/dashboard/system-41-link -> /nix/store/7qk19pkwgq0h3a1q9dcql3nks40rr75s-nixos-system-iron-16.03.1340.5a090dd | ||
... | ... | ||
/nix/var/nix/profiles/per-container/ttt/system-1-link - | /nix/var/nix/profiles/per-container/ttt/system-1-link -> /nix/store/1kj9qs5gl3421jlkl3jfc2kqdsl8akwr-nixos-system-ttt-16.03.977.1da05df | ||
/nix/var/nix/profiles/per-user/danbst/channels-1-link - | /nix/var/nix/profiles/per-user/danbst/channels-1-link -> /nix/store/s0qay9qyqrn92zayldbvvj3zrfcl7a72-user-environment | ||
/nix/var/nix/profiles/per-user/danbst/profile-28-link - | /nix/var/nix/profiles/per-user/danbst/profile-28-link -> /nix/store/69ds606146dqml04sm0fbpqwnv2w8i3q-user-environment | ||
/nix/var/nix/profiles/per-user/ec2-user/profile-7-link - | /nix/var/nix/profiles/per-user/ec2-user/profile-7-link -> /nix/store/y2hc7zsnkzys9ba6xaijvjhff03rcgpy-user-environment | ||
/nix/var/nix/profiles/per-user/root/channels-4-link - | /nix/var/nix/profiles/per-user/root/channels-4-link -> /nix/store/254b6pkhhnjywvj5c0lp2vdai8nz4p0g-user-environment | ||
/nix/var/nix/profiles/system-398-link - | /nix/var/nix/profiles/system-398-link -> /nix/store/wmndyzzrbc9fyjw844jmvzwgwgcinq7s-nixos-system-iron-16.0916.09pre.custom | ||
/root/forkstat/result - | /root/forkstat/result -> /nix/store/i5glmg3wk2a48x52rhd92zip1cmc0kq9-forkstat-git | ||
/run/booted-system - | /run/booted-system -> /nix/store/8jkrl9jyq7hqxb6xpwcaghpdm26gq98j-nixos-system-iron-16.0916.09pre.custom | ||
/run/current-system - | /run/current-system -> /nix/store/wmndyzzrbc9fyjw844jmvzwgwgcinq7s-nixos-system-iron-16.0916.09pre.custom</syntaxhighlight> | ||
=== Don't forget to run <code>nix-collect-garbage -d</code> with <code>sudo</code> === | === Don't forget to run <code>nix-collect-garbage -d</code> with <code>sudo</code> === | ||
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If you use <code>nix-build</code>, but don't use <code>--no-build-output</code>, your FS will be filled with <code>result</code> symlinks to various derivations. In example above there are | If you use <code>nix-build</code>, but don't use <code>--no-build-output</code>, your FS will be filled with <code>result</code> symlinks to various derivations. In example above there are | ||
< | <syntaxhighlight lang="bash">/home/danbst/stack/new/website/server/result -> /nix/store/1jhmp6vl364p32r8bjigk65qh1xa562f-server-0.1.0.0 | ||
/home/ec2-user/result - | /home/ec2-user/result -> /nix/store/q35aq2sh5dbyka6g6f6qb7b8msxwds5m-nixos-system-iron-16.03.1299.a8e0739 | ||
/root/forkstat/result - | /root/forkstat/result -> /nix/store/i5glmg3wk2a48x52rhd92zip1cmc0kq9-forkstat-git</syntaxhighlight> | ||
How much do these (apparently) abandoned derivations take space? | How much do these (apparently) abandoned derivations take space? | ||
< | <syntaxhighlight lang="bash">$ du -sch $(nix-store -qR /root/forkstat/result /home/ec2-user/result /home/danbst/stack/new/website/server/result) | ||
... | ... | ||
3.4G total</ | 3.4G total</syntaxhighlight> | ||
Wow, garbage? Not so much, but: | Wow, garbage? Not so much, but: | ||
< | <syntaxhighlight lang="bash"># rm /root/forkstat/result /home/ec2-user/result /home/danbst/stack/new/website/server/result | ||
# nix-collect-garbage -d | # nix-collect-garbage -d | ||
... | ... | ||
690 store paths deleted, 1817.99 MiB freed</ | 690 store paths deleted, 1817.99 MiB freed</syntaxhighlight> | ||
Especially look for system derivations. Those are created in many cases, for example, when running <code>nixos-rebuild build-vm</code> | Especially look for system derivations. Those are created in many cases, for example, when running <code>nixos-rebuild build-vm</code> | ||
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When you invoke <code>nix-shell</code> with | When you invoke <code>nix-shell</code> with | ||
< | <syntaxhighlight lang="bash">nix-shell --indirect --add-root $DIR/.nix-gc-roots/shell.drv ...</syntaxhighlight> | ||
then you'll have a persistent environment which won't be garbage collected. It is useful when you don't want to spend time waiting for redownloads every time you enter the shell. | then you'll have a persistent environment which won't be garbage collected. It is useful when you don't want to spend time waiting for redownloads every time you enter the shell. | ||
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Run <code>nix-store --optimise</code> in case you really need some a bit of space. It is a lengthy operation, and after multiple-outputs PR landing, it became less useful. | Run <code>nix-store --optimise</code> in case you really need some a bit of space. It is a lengthy operation, and after multiple-outputs PR landing, it became less useful. | ||
< | <syntaxhighlight lang="bash"># nix-store --optimise | ||
985.41 MiB freed by hard-linking 251942 files</ | 985.41 MiB freed by hard-linking 251942 files</syntaxhighlight> | ||