Evaggelos Balaskas - System Engineer

Working with VPS (Virtual Private Server), sometimes means that you dont have a lot of memory.

That’s why, we use the swap partition, a system partition that our linux kernel use as extended memory. It’s slow but necessary when your system needs more memory. Even if you dont have any free partition disk, you can use a swap file to add to your linux system.

Create the Swap File

[root@centos7] # dd if=/dev/zero of=/swapfile count=1000 bs=1MiB
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 3.62295 s, 289 MB/s

[root@centos7] # du -sh /swapfile
1.0G    /swapfile

That is 1G file

Make Swap

[root@centos7] # mkswap -L swapfs /swapfile
Setting up swapspace version 1, size = 1048572 KiB
LABEL=swapfs, UUID=d8af8f19-5578-4c8e-b2b1-3ff57edb71f9

Permissions

[root@centos7] # chmod 0600 /swapfile

Activate

[root@centos7] # swapon /swapfile

Check

# free
              total        used        free      shared  buff/cache   available
Mem:        1883716     1613952       79172       54612      190592       64668
Swap:       1023996           0     1023996

fstab

Now for the final step, we need to edit /etc/fstab

/swapfile   swap    swap    defaults    0   0

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An amazing book about IT and devops philosophy, you have to read it.