Increase or Decrease LV Swap in CentOS 6/RHEL 6

Scenario: How to increase or decrease swap space(logical volume swap) in CentOS 6/RHEL 6

System: CentOS 6/ RHEL 6

Steps increase Swap space
Example increase 1 GB swap space.

1) You must check the path of swap logical volume and the free space in the swap volume group before continue to step 2.
# free -m
# lvdisplay | grep swap
# vgs

[root@kucing ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1877        405       1471          0         31        200
-/+ buffers/cache:        173       1703
Swap:         3071          0       3071
[root@kucing ~]# lvdisplay | grep swap
  LV Path                /dev/vg_kucing/lv_swap
  LV Name                lv_swap
[root@kucing ~]# vgs
  VG        #PV #LV #SN Attr   VSize  VFree
  data_vg     1   1   0 wz--n-  9.31g  4.31g
  vg_data2    1   1   0 wz--n-  9.31g  1.31g
  vg_kucing   2   2   0 wz--n- 39.50g 10.00g
[root@kucing ~]#

2) From step 1 we got swap space is 3GB, the swap path and free size of the swap Volume Group,then continue disable swapping for the associated logical volume:
# swapoff -v /dev/vg_kucing/lv_swap

3) Resize the LVM2 logical volume by 2 GB:
# lvresize /dev/vg_kucing/lv_swap -L +1G

4) Format the new swap space:
# mkswap -f /dev/vg_kucing/lv_swap

5) Enable the extended logical volume:
# swapon -v /dev/vg_kucing/lv_swap

[root@kucing ~]# swapoff -v /dev/vg_kucing/lv_swap
swapoff on /dev/vg_kucing/lv_swap
[root@kucing ~]# lvresize /dev/vg_kucing/lv_swap -L +1G
  Size of logical volume vg_kucing/lv_swap changed from 3.00 GiB (768 extents) to 4.00 GiB (1024 extents).
  Logical volume lv_swap successfully resized.
[root@kucing ~]# mkswap -f /dev/vg_kucing/lv_swap
Setting up swapspace version 1, size = 4194300 KiB
no label, UUID=949221bf-97a6-4ed9-a908-2b931779e798
[root@kucing ~]# swapon -v /dev/vg_kucing/lv_swap
swapon on /dev/vg_kucing/lv_swap
swapon: /dev/mapper/vg_kucing-lv_swap: found swap signature: version 1, page-size 4, same byte order
swapon: /dev/mapper/vg_kucing-lv_swap: pagesize=4096, swapsize=4294967296, devsize=4294967296
[root@kucing ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1877        405       1471          0         31        200
-/+ buffers/cache:        173       1704
Swap:         4095          0       4095
[root@kucing ~]#

Steps to decrease Swap space
Example decrease 1 GB swap space.

1) Check the path of swap logical volume.
# lvdisplay | grep swap

2) Disable swapping for the associated logical volume:
# swapoff -v /dev/vg_kucing/lv_swap

3) Reduce the LVM2 logical volume by 512 MB:
# lvreduce -L 1G /dev/vg_kucing/lv_swap

4) Format the new swap space:
# mkswap -f /dev/vg_kucing/lv_swap

5) Enable the extended logical volume:
# swapon -v /dev/vg_kucing/lv_swap

[root@kucing ~]# lvdisplay | grep swap
  LV Path                /dev/vg_kucing/lv_swap
  LV Name                lv_swap
[root@kucing ~]# swapoff -v /dev/vg_kucing/lv_swap
swapoff on /dev/vg_kucing/lv_swap
[root@kucing ~]# lvreduce -L 1G /dev/vg_kucing/lv_swap
  WARNING: Reducing active logical volume to 1.00 GiB.
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce vg_kucing/lv_swap? [y/n]: y
  Size of logical volume vg_kucing/lv_swap changed from 4.00 GiB (1024 extents) to 1.00 GiB (256 extents).
  Logical volume lv_swap successfully resized.
[root@kucing ~]# mkswap -f /dev/vg_kucing/lv_swap
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=7db2f5c6-09c7-467a-9f1b-4be3c2aac723
[root@kucing ~]# swapon -v /dev/vg_kucing/lv_swap
swapon on /dev/vg_kucing/lv_swap
swapon: /dev/mapper/vg_kucing-lv_swap: found swap signature: version 1, page-size 4, same byte order
swapon: /dev/mapper/vg_kucing-lv_swap: pagesize=4096, swapsize=1073741824, devsize=1073741824
[root@kucing ~]#

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