systemd-swap

Script to manage swap on:

zswap - Enable/Configure
zram - Autoconfigurating for swap
files - (sparse files for saving space, supports btrfs)
block devices - auto find and do swapon

ℹ️ It is configurable in /etc/systemd/swap.conf.

Additional terms:

SwapFC (File Chunked) - provides a dynamic swap file allocation/deallocation

File location

/etc/systemd/swap.conf
/usr/lib/systemd/system/systemd-swap.service
/usr/bin/systemd-swap

Please don't forget to enable and start with

sudo systemctl enable --now systemd-swap

Install

Arch: in the community.

Debian

git clone --depth=1 https://github.com/Nefelim4ag/systemd-swap.git
cd systemd-swap
make deb
sudo dpkg -i systemd-swap_*_all.deb

Fedora

git clone --depth=1 https://github.com/Nefelim4ag/systemd-swap.git
cd systemd-swap
FEDORA_VERSION=f32 make rpm
sudo rpm -U systemd-swap-*noarch.rpm

CentOS

git clone --depth=1 https://github.com/Nefelim4ag/systemd-swap.git
./systemd-swap/package.sh centos
sudo rpm -U ./systemd-swap/systemd-swap-*noarch.rpm

Manual

git clone --depth=1 https://github.com/Nefelim4ag/systemd-swap.git
sudo make install

# or into /usr/local:
sudo make prefix=/usr/local install

About configuration

Q: Do we need to activate both zram and zswap?
A: Nope, it's useless, as zram is a compressed RAM DISK, but zswap is a compressed "writeback" CACHE on swap file/disk. Also having both activated can lead to inverse LRU as noted here

Q: Do I need to use swapfc_force_use_loop on swapFC?
A: Nope, as you wish really, native swapfile should work faster and it's safer in OOM condition in comparison to loop backed scenario.

Q: When would we want a certain configuration?
A: In most cases (Notebook, Desktop, Server) it's enough to enable zswap + swapfc (on server tuning of swapfc can be needed). If you use a SSD and care about flash memory wear, use only ZRam.

Q: Can we use this to enable hibernation?
A: Nope as hibernation wants a persistent fs blocks and wants access to swap data directly from disk, this will not work on: swapfc (without some magic of course, see #85).

Note

ℹ️ Zram dependence: util-linux >= 2.26
ℹ️ If you use zram not for swap only, use kernel 4.2+ or please add rule for modprobe like:
```
options zram max_devices=32
```

Switch on systemd-swap:s automatic swap management

Enable swapfc if wanted (note, you should never use zram and zswap at the same time, read more here)
```
vim /etc/systemd/swap.conf
```
```
zram_enabled=0
zswap_enabled=1
swapfc_enabled=1
```
Stop any external swap:
```
sudo swapoff -a
```
Remove swap entry from fstab:
```
vim /etc/fstab
```

Remove your swap

# For Ubuntu
sudo rm -f /swapfile

# For Centos 7 (if using a swap partition and lvm)
lvremove -Ay /dev/centos/swap
lvextend -l +100%FREE centos/root

Remove swap from Grub:

# For Ubuntu remove resume* in grub
vim /etc/default/grub

# For Centos 7 remove rd.lvm.lv=centos/swap*
vim /etc/default/grub

# For Manjaro remove resume* in grub & mkinitcpio
vim /etc/default/grub
vim /etc/mkinitcpio.conf

# For Ubuntu
update-grub

# For Centos 7
grub2-mkconfig -o /boot/grub2/grub.cfg

# For Manjaro
update-grub
mkinitcpio -P

r3b311i0n / systemd-swap