How to Add Swap Memory in Centos 7?

Today I got 10 emails from my web hosting, all about High Memory Usage Messages. My hosting is 2 cores, 4 GB memories, online on Magento 2.3,6 based glasses shop for https://www.optical4u.com. I am using Centos 7, Nginx.

I forgot the position of the swap memory location, we can use one of the following method to check the swap file location.

swapon -s
cat /proc/swaps
cat /etc/fstab
cat /etc/fstab | grep -i swap

I think I may set the swap memory too small. So I plan to delete the 2 GB swap memories:

[glasses@optical4u /]# cat /etc/fstab | grep -i swap
/var/swapfile swap swap defaults 0 0

Delete the swap memory by running:

swapoff /var/swapfile
rm -rf /var/swapfile

Now let’s check memory information:

free -m
Swap 0 0 0

Create a 6 GB swap memory:

dd if=/dev/zero of=/var/swapfile  bs=1024 count=6144000

mkswap /var/swapfile

swapon /var/swapfile

Check swap memory again:

free
Swap:       6143996           0     6143996

In order to let the swap memory run automatically, edit vim /etc/fstab.

Delete:


/swap none swap sw 0 0

Add：


/usr/swap/swapfile swap swap defaults 0