How to Increase SWAP Partition on Linux

Let's see the current size of SWAP.

We have 4GB in a partition for SWAP mounted at /dev/dm-1. (Note: This command is equivalent to swapon -s.)

There're two ways to increase the SWAP size of a host.

1. Add a swap file.

This could be the easiest way to do it. Please refer to the following post for more information: How to Enable a Swap File on CentOS 6.5

2. Increase SWAP logical volume

First, let's check the name of the logical volume of SWAP in this host.

[root@test ~]# lvdisplay
...
  --- Logical volume ---
  LV Path                /dev/vg_test/lv_swap
  LV Name                lv_swap
  VG Name                vg_test
  LV UUID                219bOE-3aD7-UPX4-IS51-5QZd-X2nG-dLh1fY
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2015-07-29 22:47:16 +0800
  LV Status              available
  # open                 2
  LV Size                3.91 GiB
  Current LE             1000
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:1

Next, let's see how much free space we have now.

[root@test ~]# vgs
  VG           #PV #LV #SN Attr   VSize  VFree
  vg_test        1   3   0 wz--n- 79.51g 5.60g

You can see there's 5.6GB left in the volume group vg_test. If there's no enough space for SWAP. you may reduce the size of other logical volumes to squeeze the space: How to Reduce Volume Size on Enterprise Linux.

Turn the SWAP volume off.

[root@test ~]# swapoff /dev/vg_test/lv_swap

Add more space (i.e. +2GB) to the SWAP volume.

[root@test ~]# lvextend -L +2GB /dev/vg_test/lv_swap
  Size of logical volume vg_test/lv_swap changed from 3.91 GiB (1000 extents) to 5.91 GiB (1512 extents).
  Logical volume lv_swap successfully resized

Reformat the SWAP volume.

[root@test ~]# mkswap /dev/vg_test/lv_swap
mkswap: /dev/vg_test/lv_swap: warning: don't erase bootbits sectors
        on whole disk. Use -f to force.
Setting up swapspace version 1, size = 6193148 KiB
no label, UUID=5c2765cf-9efe-44be-9fa0-679f185b2086

Turn the SWAP volume on.

[root@test ~]# swapon /dev/vg_test/lv_swap

Let's see the result.

[root@test ~]# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       6193148 0       -1

Please note that, the content of /proc/swaps is the same as the command swapon -s.