Introduction
Managing swap space efficiently is essential for optimal Linux performance, especially when handling memory-intensive applications. Sometimes, Oracle databases or Oracle Enterprise manager or any other application which is asking for swap will fail installations. This guide covers three common scenarios to Increase swap size in Linux:
- When no swap is available.
- When swap is already available but needs expansion.
- When swap is created using a file.
Follow these step-by-step instructions to optimize your system’s performance with proper swap management. We will create 4G swap space
Checking Current Swap Space
Before modifying swap, check the existing swap space:
sudo swapon --summary
or
free -h
If no swap is available, the output will show 0B under the swap column.
Case 1: Adding Swap When No Swap is Available
Step 1: Create a Swap File
sudo fallocate -l 4G /swapfile
If fallocate is not available, use:
sudo dd if=/dev/zero of=/swapfile bs=1M count=4096
Please be aware that Before creating this file, you should check the storage available on root file system (/). If no storage available, you may need to Add/extend the storage.
Step 2: Set Permissions
sudo chmod 600 /swapfile
Step 3: Format the File as Swap
sudo mkswap /swapfile
Step 4: Enable the Swap File
sudo swapon /swapfile
Step 5: Make Swap Permanent
Add the following line to /etc/fstab:
/swapfile none swap sw 0 0
Case 2: Increasing Existing Swap Space
Step 1: Turn Off Current Swap
sudo swapoff -a
Step 2: Resize or Add More Swap Space
Option 1: Extend Swap Partition (If Using a Partition)
- Use tools like
fdisk,parted, orgpartedto resize the swap partition. - Run
sudo mkswap /dev/sdX(replacesdXwith your swap partition).
Option 2: Create an Additional Swap File
If modifying partitions is not feasible, create another swap file (refer to Case 1 steps) and enable it:
sudo swapon /swapfile02
Step 3: Verify Swap Space
free -h
Case 3: Creating Swap Using a File
Step 1: Allocate Swap Space
sudo fallocate -l 4G /swapfile
We will use “swapfile” file name for this purpose
Step 2: Secure Swap File
sudo chmod 600 /swapfile
Step 3: Convert to Swap Format
sudo mkswap /swapfile
Step 4: Enable Swap
sudo swapon /swapfile
Step 5: Make It Persistent
Edit /etc/fstab and add:
/swapfile none swap sw 0 0
Optimizing Swap Performance
To adjust swappiness (how often swap is used), modify the value in /etc/sysctl.conf:
echo "vm.swappiness=10" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p
Conclusion
Increase swap size in Linux can improve system performance and prevent out-of-memory errors. Whether adding swap for the first time, expanding existing swap, or using a file-based swap, following these steps ensures your Linux system runs smoothly.
Related Topics
- How to Monitor Swap Usage in Linux
- Best Practices for Linux Memory Management
- Understanding Swappiness in Linux
Let us know in the comments if you have any questions!