centos create a swap partition

The cloud server no default swap, as follows:

[root@myhost ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1839         694          77           0        1068         949
Swap:             0           0           0

　

Create a swap partition, the swap should be set on how much of it?

4GB or 4GB or less of memory systems, the minimum required 2GB swap space; 
greater than 4GB and less than 16GB memory system, minimum required 4GB swap space; 
greater than 16GB and less than 64GB memory system, minimum required 8GB swap space; 
greater than 64GB and less than 256GB memory the system requires a minimum 16GB swap space.

　

Add a swap partition:

IF = dd / dev / ZERO of = / = 1K the swapfile BS COUNT = 2048000 
2. Create SWAP file 
# the mkswap / the swapfile 
3. Activate SWAP file 
# the swapon / the swapfile 
4. Check SWAP information is correct 
# the swapon -s 
5. The added to fstab file to start automatically when the system boot 
# echo "/ var / swapfile swap swap Defaults 0 0" >> / etc / fstab 
6. check with the command free 2G swap to take effect 
# free -m 
# grep SwapTotal / proc / meminfo 
7 The release SWAP file 
# swapoff / swapfile 
8. delete SWAP file 
# rm -fr / swapfile