- How to add Swap space
- Create a swap file
- Enable the swap file
- Make swap permanent
- Tweak your swap setting
This is a new post and it is sister message for http://www.aftermath.cn/kvms-resize.html
How to add Swap space
First, we can see if the filestsyem has any swap, you can type:
sudo swapon --show
If any thing does not display, this means your system does not have any swap space.
You can verify there is no active swap using free
utility:
free -h
total used free shared buff/cache available Mem: 2.0G 105M 262M 11M 1.6G 1.7G Swap: 0B 0B 0B
Via df -h
to check disk space
Create a swap file
sudo fallocate -l 2G /swapfile
The program fallocate
to create a file named swapfile
in our (/) directory.
Because we have a RAM is 1024MB, so we create a swapfile which space is 2G.
ls -hl /swapfile
You can verify it now.
Enable the swap file
Now, we do not turn this into swap space.Make the file only accessible to root
by typing:
sudo chmod 600 /swapfile
Next, type:
sudo mkswap /swapfile
Then, to start utilizing it:
sudo swapon /swapfile
So, we have finished it.
sudo df -h
sudo free -h
Make swap permanent
Yes, it is in use on this start,you have to add it into /etc/fstab
First, back up your /etc/fstab
. Then,
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
Tweak your swap setting
The swappiness
parameter configures how often your system swaps data out of RAM to the space. This is a value between 0 ans 100 that represents a percentage.
If you have a deskop machine, the 60
is ok, but for server, it is better 0.
cat /proc/sys/vm/swappiness
It will show on my machine:
60
We can set the swappiness to a different value by using the sysctl
command.
sudo sysctl.swappiness=10
If you want to it persent permenant , edit /etc/sysvtl.conf
file to add:
vm.swappiness = 10