Swap setup
Setup swap files in RAM and btrfs filesystems.
Use a swap file (in btrfs)¶
Swap files are more flexible than swap partitions in terms of disk space and partition usage.
Source: btrfs docs and Arch Linux wiki.
The following commands create a swap file in the btrfs filesystem, which does not (and should not) use copy-on-write (COW).
sudo btrfs subvolume create /swap # Create a btrfs subvolume for the swap file's directory
sudo btrfs filesystem mkswapfile --size 4G --uuid clear /swap/swapfile # Create a 4 GB swap file
sudo swapon /swap/swapfile
If btrfs filesystem mkswapfile
command is not available, use the following command
cd /swap
sudo truncate -s 0 /swap/swapfile
sudo chattr +C /swap/swapfile
sudo fallocate -l 4G /swap/swapfile
sudo chmod 0600 /swap/swapfile
sudo mkswap /swap/swapfile
sudo swapon /swap/swapfile
Add the following line to /etc/fstab
to mount the swap file on next boot.
See the current activated swap file(s):
Use ZRAM¶
ZRAM is a compressed RAM disk, which can be used as a swap device to reduce physical disk swap use under high memory pressure.
Install ZRAM in Ubuntu: Source
edit /etc/default/zramswap
to change the options.
enable
check ZRAM status