Alex Ruben
How To Clear Swap Space When Free RAM Is Available in Linux/Ubuntu
How to Clear Swap Space When You Have Free RAM on Linux
Ever run into this weird situation where, despite having plenty of free RAM, your Linux system is still chewing up swap? This can slow things down, especially if the swap is on a slower disk. Clearing swap when it’s unnecessarily being used can boost responsiveness, especially on systems with limited resources or those that got stuck in swap mode for some reason. But here’s the catch: if the system is actively using swap, then shutting it off temporarily moves data back into RAM. If your RAM is really free, that usually works fine—but it’s kind of a balancing act.
Basically, this is handy if you notice your swap is lightly used, but you know your RAM can handle more. Just keep in mind, if you’re running heavy apps or your RAM is close to full, turning off swap could cause issues. On some setups, you might see that swap usage drops immediately after turning it off, then it reappears if the system starts swapping again. So, it’s not a permanent fix, but more of a quick refresh to hopefully free up some disk I/O.
How to Clear Swap on Linux — Step-by-Step
Check current RAM and swap usage
First, you gotta know what’s going on. Run free -h in your terminal. You’ll see a snapshot of RAM and swap usage. If swap shows some used space but your RAM is mostly free, then you’re probably good to try clearing it out. If swap is fully utilized and your RAM is also maxed, be careful with this method — might cause performance hiccups or crashes.
Turn off swap safely
This is the critical part. Disabling swap with sudo swapoff -a tells your Linux to stop swapping and moves what’s in swap back into RAM. This is the real trick—if some old data is hanging out there, turning off swap forces it to return to RAM, freeing up disk space. Just be aware: on some systems, if there isn’t enough free RAM, this could cause activity slowdown, or apps might crash if they run out of memory. So, best to do this when system usage is low.
Pro tip: Some folks report that on certain machines, this command might fail initially — usually because not enough free RAM or a busy system. In that case, closing heavy programs before attempting this helps.
Re-enable swap after clearing
Once swap is off and you’re happy with the cleanup, just turn it back on with sudo swapon -a. This restores swap functionality in case your system needs it later. It’s a good habit to do this, so your system doesn’t get caught without swap if things get heavy.
On some setups, it’s worth checking your swap space configuration in /etc/fstab—especially if you’re experimenting with permanently disabling swap, which is usually not recommended unless you know what you’re doing.
Extra Tips & Troubleshooting
Between turns, keep an eye on your resource usage. Use free -h frequently to see if your RAM stays free after turning swap back on. If swap keeps filling up, maybe your system is under more pressure than expected. Adjusting the swappiness parameter can influence how aggressively Linux uses swap; you can change it temporarily with:
sudo sysctl vm.swappiness=10This decreases swap tendency. To make it permanent, add vm.swappiness = 10 to /etc/sysctl.conf.
Another thing: If swap fills back up quickly after turning it on, check what processes are using memory with top or htop. Sometimes a runaway process is the culprit.
Wrap-up
This whole process isn’t magic, but it’s a quick way to free up swap and maybe get your system feeling snappier. Remember, don’t do this if your RAM’s already maxed out. The main goal is to give your system some breathing room without risking crashes or instability. On one setup it worked like a charm, on another… not so much, but worth trying if you’re trying to squeeze some extra performance.
Summary
- Check swap and RAM use with
free -h - Safely turn swap off with
sudo swapoff -a - Turn swap back on with
sudo swapon -a - Optional: tweak swappiness to manage swap behavior
- Always monitor your system afterward to avoid surprises
Fingers crossed this helps
Hopefully, this shaves off a few hours for someone wrestling with swap issues. It’s kind of weird, but sometimes clearing swap can give your system a little extra turbo boost, especially when it’s been stuck in swap mode for no good reason. Just remember to keep an eye on your memory usage before and after — because of course, Linux has to make it harder than necessary, right?