Increase SWAP size in CentOS7.7

CentOS7.7 the installation default swap, swap done using the lvm lv, when necessary to increase the swap space, may be considered as follows:

1. Current state

[root@syk01 ~]# swapon -s
文件名             类型      大小  已用  权限
/dev/dm-1                               partition   2097148 0   -2

[root@syk01 ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao---- 36.99g
  swap centos -wi-ao----  2.00g

2. Close the current swap

[root@syk01 ~]# swapoff -v /dev/mapper/centos-swap
swapoff /dev/mapper/centos-swap

[root@syk01 ~]# swapon -s

3. The size of the expansion lv

[root@syk01 ~]# lvresize /dev/mapper/centos-swap -L +1g
  Size of logical volume centos/swap changed from 2.00 GiB (512 extents) to 3.00 GiB (768 extents).
  Logical volume centos/swap successfully resized.

[root@syk01 ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao---- 36.99g
  swap centos -wi-a-----  3.00g

4. Format swap space

[root@syk01 ~]# mkswap -f /dev/mapper/centos-swap
mkswap: /dev/mapper/centos-swap: warning: wiping old swap signature.
正在设置交换空间版本 1，大小 = 3145724 KiB
无标签，UUID=26c45e5f-636f-4569-9c8f-197bee4dd56e

5. Open a new swap space

[root@syk01 ~]# swapon -v /dev/mapper/centos-swap
swapon /dev/mapper/centos-swap
swapon: /dev/mapper/centos-swap：找到交换区签名：版本为 1，页面大小为 4，相同 字节顺序
swapon: /dev/mapper/centos-swap：页大小=4096，交换区大小=3221225472，设备大小=3221225472

[root@syk01 ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1837         140        1519           8         178        1660
Swap:          3071           0        3071
[root@syk01 ~]#