# BTRFS Swap "Not enough swap space for hibernation"
**URL:** https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805
**Category:** Help
**Created:** [December 13, 2023, 3:13pm UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805 "2023-12-13T15:13:00Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@charmoniumQ](https://discourse.nixos.org/u/charmoniumQ)
#### Post date: [December 13, 2023, 3:13pm UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805/1 "2023-12-13T15:13:01Z")
`systemctl hibernate` says `Not enough swap space`, but `free -h` indicates that “free” swap is greater than “total” mem.
```auto
$ systemctl hibernate
Call to Hibernate failed: Not enough swap space for hibernation
$ free -h
total used free shared buff/cache available
Mem: 15Gi 6.8Gi 199Mi 2.5Gi 8.4Gi 5.8Gi
Swap: 23Gi 9.0Mi 23Gi
```
If it matters (which I don’t think it should), my swap partition is a btrfs subvolume on luks encrypted disk.
```auto
$ swapon
NAME TYPE SIZE USED PRIO
/swap/swapfile file 24G 139.2M -2
$ mount -v | grep swap
/dev/mapper/crypted on /swap type btrfs (rw,relatime,compress=zstd:3,ssd,noacl,space_cache=v2,subvolid=260,subvol=/swap)
$ cat /etc/fstab | grep -i swap
# To make changes, edit the fileSystems and swapDevices NixOS options
/dev/mapper/crypted /swap btrfs subvol=swap 0 0
# Swap devices.
/swap/swapfile none swap defaults
$ sudo btrfs sub list / | grep swap
ID 260 gen 6590 top level 5 path swap
```
My disk configuration [here](https://github.com/charmoniumQ/homelab/blob/54b6091da5fb52d43d94e6aff1ebb42dbebbc23c/hosts/laptop/disko.nix). It uses disko, so I found it easier to just `nix repl` and evaluate whatever attributes you need to answer the question.
```auto
$ nix repl '.#nixosConfigurations.laptop'
Welcome to Nix 2.19.2. Type :? for help.
Loading installable 'git+file:///home/sam/box/homelab#nixosConfigurations.laptop'...
Added 9 variables.
nix-repl> config.boot.kernelParams
["acpi_osi=\"!Windows 2020\"" "nvme.noacpi=1" "loglevel=4"]
(some NixOS systems would have "nohibernate" in here; not me.)
nix-repl> config.fileSystems
{ "/" = { ... }; "/boot" = { ... }; "/home" = { ... }; "/nix" = { ... }; "/persist" = { ... }; "/swap" = { ... }; "/var/log" = { ... }; }
nix-repl> config.fileSystems."/swap"
{ autoFormat = false; autoResize = false; depends = [...]; device = "/dev/mapper/crypted"; encrypted = { ... }; formatOptions = null; fsType = "btrfs"; label = null; mountPoint = "/swap"; neededForBoot = false; noCheck = false; options = [...]; stratis = { ... }; }
nix-repl> config.swapDevices
[{ ... }]
nix-repl> (builtins.head config.swapDevices).device
"/swap/swapfile"
```
---
### Author:  [@Solene](https://discourse.nixos.org/u/Solene)
#### Post date: [December 13, 2023, 3:17pm UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805/2 "2023-12-13T15:17:42Z")
In journalctl or dmesg you may have the reason why it doesn’t want to hibernate.
For instance, if the swap file is on a BTRFS volume spread across more than 1 disk, it will refuse.
---
### Author:  [@charmoniumQ](https://discourse.nixos.org/u/charmoniumQ)
#### Post date: [December 13, 2023, 3:30pm UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805/3 "2023-12-13T15:30:49Z")
Neither `journalctl` nor `dmesg` contain the word “swap” or “hibernate” case insensitive. Not sure what’s going on here.
---
### Author:  [@be9857](https://discourse.nixos.org/u/be9857)
#### Post date: [December 22, 2023, 6:57pm UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805/4 "2023-12-22T18:57:05Z")
same configuration here and same problem
also nothing shows in my journalctl or dmesg
---
### Author:  [@simplejack-src](https://discourse.nixos.org/u/simplejack-src)
#### Post date: [December 23, 2023, 12:27am UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805/5 "2023-12-23T00:27:00Z")
I had this error myself (couple releases ago). In my particular issue it was a systemd bug (not sure if its still a bug or the same issue your hitting). In my particular case the workaround (knowing that the swap size is of sufficient size):
```auto
# In your NixOS configuration
systemd.services.systemd-logind.environment = {
SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK = "1";
};
```
---
### Author:  [@be9857](https://discourse.nixos.org/u/be9857)
#### Post date: [December 23, 2023, 6:51pm UTC](https://discourse.nixos.org/t/btrfs-swap-not-enough-swap-space-for-hibernation/36805/6 "2023-12-23T18:51:03Z")
@Solene
good news I found some new context using @simplejack-src hacks
so at least we know where is the problem
and make this bug report
[https://github.com/NixOS/nix/issues/9660](https://github.com/NixOS/nix/issues/9660)