How to Add Swap Memory

Prerequisites

Before adding swap memory, make sure you have:

• SSH access to your VPS (username: hxroot)
• Your server IP address and root password
• At least 10-20% free disk space for swap file

Step 1: Check Current Swap Usage

Connect to your VPS:

ssh hxroot@YOUR_SERVER_IP -p 22

Check memory and swap status:

free -h

Example output with no swap:

              total        used        free      shared  buff/cache   available
Mem:           3.8G        2.1G        1.1G        123M        700M        1.4G
Swap:            0B          0B          0B

Step 2: Check Disk Space

df -h

Ensure you have enough free space for the swap file (recommended 1-2x RAM).

Step 3: Create Swap File

For a 2GB swap file (adjust size as needed):

sudo fallocate -l 2G /swapfile

If fallocate is not available, use dd:

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

Step 4: Set Correct Permissions

sudo chmod 600 /swapfile

Only root should read/write swap file for security.

Step 5: Format as Swap

sudo mkswap /swapfile

Example output:

Setting up swapspace version 1, size = 2 GiB (2147483648 bytes)
no label, UUID=abc123-def456-ghi789

Step 6: Enable Swap

sudo swapon /swapfile

Step 7: Verify Swap is Active

free -h

Should now show swap space:

              total        used        free      shared  buff/cache   available
Mem:           3.8G        2.1G        1.1G        123M        700M        1.4G
Swap:          2.0G          0B        2.0G

Also check with:

sudo swapon --show

Step 8: Make Swap Permanent (Auto-mount on Boot)

Add to /etc/fstab:

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

Verify the entry:

cat /etc/fstab | grep swap

How Much Swap Should You Add?

General guidelines:

• RAM ≤ 2GB → Swap = 2x RAM
• RAM 2GB - 8GB → Swap = same as RAM
• RAM 8GB - 64GB → Swap = 4GB to 8GB
• RAM > 64GB → Swap = 4GB minimum

Hostxpeed VPS recommendations:

• 2GB RAM VPS → 2GB swap
• 4GB RAM VPS → 4GB swap
• 8GB RAM VPS → 4GB swap
• 16GB+ RAM VPS → 4-8GB swap

Adjust Swappiness (How Often Swap is Used)

Swappiness value (0-100, default 60):

cat /proc/sys/vm/swappiness

To reduce swap usage (for servers with enough RAM):

sudo sysctl vm.swappiness=10

Make permanent by adding to /etc/sysctl.conf:

echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf

Remove Swap (If Needed)

To disable and remove swap:

sudo swapoff /swapfile

sudo rm /swapfile

Remove the line from /etc/fstab.

Monitor Swap Usage

Check swap in real-time:

free -h -s 5

See which processes use swap:

sudo smem --swap

Or:

for file in /proc/*/status ; do awk '/VmSwap|Name/{printf $2 " " $3}END{ print ""}' $file 2>/dev/null; done | sort -k 2 -n -r | head -10