Check current swap usage with free -h or swapon --show and review /proc/swaps to determine if additional swap is needed. 2. Create a swap file using fallocate or dd, set permissions with chmod 600, format with mkswap, enable with swapon, and make it persistent by adding an entry to /etc/fstab. 3. Adjust swappiness by checking the current value in /proc/sys/vm/swappiness and setting a new value like vm.swappiness=10 via sysctl and /etc/sysctl.conf to reduce unnecessary swapping. 4. Remove swap by disabling it with swapoff, deleting the file, and removing the /etc/fstab entry, or resize it by repeating the creation steps with a new size. Best practices include sizing swap as 2× RAM for systems with ≤4GB RAM, 8GB or equal to RAM for hibernation, preferring swap files over partitions, placing swap on SSDs, and monitoring usage with tools like htop or vmstat. Proper swap management enhances system stability and performance under memory pressure.

Managing swap space on a Linux system is an important part of system administration, especially when dealing with memory-intensive applications or systems with limited RAM. Swap space acts as overflow memory — when physical RAM is full, less-used pages are moved to swap, freeing up RAM for active processes. While not as fast as RAM, proper swap configuration can prevent out-of-memory crashes and improve system stability.

Here’s how to effectively manage swap space on a Linux system.

1. Check Current Swap Usage

Before making changes, check how much swap is currently in use:

free -h

or

swapon --show

This will show total, used, and available swap space. You can also view detailed memory and swap usage with:

cat /proc/swaps

This helps you understand whether your system is actively using swap and how much is configured.

2. Create and Enable a Swap File

If your system lacks sufficient swap, you can add a swap file. Here's how:

1. Create a file of desired size (e.g., 2GB):

   sudo fallocate -l 2G /swapfile

   If fallocate fails (e.g., on some filesystems), use:

   sudo dd if=/dev/zero of=/swapfile bs=1M count=2048

2. Set proper permissions (only root should read/write):

   sudo chmod 600 /swapfile

3. Format the file as swap:

   sudo mkswap /swapfile

4. Enable the swap file:

   sudo swapon /swapfile

5. Make it persistent across reboots by adding to /etc/fstab:

   echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Now the system will use the new swap file on every boot.

3. Adjust Swappiness for Better Performance

Swappiness controls how aggressively the kernel swaps data out of RAM. It’s a value from 0 to 100:

• 0: Avoid swap unless absolutely necessary (out of memory)
• 60: Default value on most distributions
• 100: Try to keep RAM as free as possible by swapping more

To check current swappiness:

cat /proc/sys/vm/swappiness

For a desktop or low-latency system, reduce swappiness:

sudo sysctl vm.swappiness=10

To make it permanent, edit /etc/sysctl.conf:

vm.swappiness=10

On servers with plenty of RAM, lowering swappiness can reduce disk I/O and improve responsiveness.

4. Remove or Resize Swap (If Needed)

To remove a swap file:

1. Disable it:

   sudo swapoff /swapfile

2. Remove the entry from /etc/fstab

3. Delete the file:

   sudo rm /swapfile

   To resize, repeat the creation steps with a new size and re-enable.

   ---

   Best Practices

   • Size Guidelines:

     • For systems with ≤ 4GB RAM: Swap = 2× RAM
     • For 8GB RAM: Swap = 8GB (or less, depending on workload)
     • For hibernation: Swap ≥ RAM size (needed to store memory state)

   • Use swap files over partitions (modern Linux supports this well; easier to resize)

   • Place swap on fast storage — SSDs significantly improve swap performance

   • Monitor regularly with tools like htop, vmstat, or sar

   ---

   Managing swap space doesn’t have to be complex, but it plays a key role in system stability. With the right size and tuning, you can balance performance and reliability — especially under memory pressure.

   Basically: check usage, add a swap file if needed, tweak swappiness, and monitor. That’s most of what you’ll ever need.

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