How to manage Linux swap and zram

· Category: Linux

Short answer

Combine traditional swap with zram to improve performance by compressing memory pages instead of writing them to slow disks.

Steps

  1. Enable zram:
sudo modprobe zram num_devices=1
sudo zramctl /dev/zram0 --size 2G
sudo mkswap /dev/zram0
sudo swapon /dev/zram0
  1. Make persistent with a systemd service or zram-generator.
  2. Monitor swap usage:
free -h
cat /proc/swaps

Tips

  • zram is ideal for low-memory systems like Raspberry Pi.
  • Use swap on SSD for hibernation; zram cannot hibernate.
  • vm.swappiness controls how aggressively the kernel swaps.

Common issues

  • zram uses CPU for compression; monitor load on weak CPUs.
  • Without persistent config, zram is lost on reboot.