I have a virtual machine (hosted online) with 2Gb swap space.

free -m

             total       used       free     shared    buffers     cached
Mem:          1995        438       1557         37         22        190
-/+ buffers/cache:        225       1770
Swap:         1998          0       1998

Since the swap space was small, I tried to increase it to 4GB.

Doing swapon -s, returned this result (not sure what it means since I don't have a second hard disk sda2)

Filename                                Type            Size    Used    Priority
/dev/sda2                               partition       2046972 0       -1

df -H

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        25G   19G  4.3G  82% /
udev            1.1G  4.1k  1.1G   1% /dev
tmpfs           210M  492k  209M   1% /run
none            4.1k     0  4.1k   0% /sys/fs/cgroup
none            5.3M     0  5.3M   0% /run/lock
none            1.1G     0  1.1G   0% /run/shm
none            105M     0  105M   0% /run/user

So I did

swapoff -a                #deactivating previous swap space
fallocate -l 4G /swapfile #creating a swapfile
chmod 600 /swapfile       #giving permissions
mkswap /swapfile          #making swap the file
swapon /swapfile          #activating swap on the file
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab #stabilizying swap for it to be there after next reboot

Now I have the swap space I needed

free -m

             total       used       free     shared    buffers     cached Mem:          1995       1153        842         64        116 
-/+ buffers/cache:        581       1414 Swap:         4095          0       4095

But, the 2GB of the previous swap space are still considered occupied if I do a df (maybe they will be free at the next reboot?) and my fstab has two entries for swap space.

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
/dev/sda1       /       ext4    errors=remount-ro,relatime      0       1
/dev/sda2       swap    swap    defaults        0       0
proc            /proc   proc    defaults                0       0
sysfs           /sys    sysfs   defaults                0       0
devtmpfs        /dev    devtmpfs        rw      0       0
/swapfile none swap sw 0 0

In this situation, how I may proceed to finalize the procedure? I have to remove the second line referring to swap in the fstab? (I mean /dev/sda2 swap swap defaults 0 0) It is safe to reboot?

  • /dev/sda2 is a second partition on your computer. That is, it shares space on your disk - you can see this in sudo fdisk -l /dev/sda output. Removing the partition will be difficult while you're running the system; it can be done but you won't be able to recover the space to use on the ext4 partition while you're running the system. Jan 9, 2019 at 14:35
  • I would have add only 2G and keep both swap area, with device in higher priority. (see man 8 swapon)
    – Archemar
    Jan 9, 2019 at 14:49


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