Linux内存不足增加虚拟内存的方法

a) Login as the root user SSH登录root 账户
b) Type following command to create 2G swap file (1024 * 2048MB = 2097152 block size):

dd if=/dev/zero of=/swapfile1 bs=1024 count=2097152

c) Set up a Linux swap area:

mkswap /swapfile1

d) Activate /swapfile1 swap space immediately:

swapon /swapfile1

e) To activate /swapfile1 after Linux system reboot, add entry to /etc/fstab file. Open this file using text editor such as vi:

vi /etc/fstab

Append following line:

/swapfile1 swap swap defaults 0 0

So next time Linux comes up after reboot, it enables the new swap file for you automatically.
g) How do I verify swap is activated or not?
Simply use free command:

$ free -m

如果想关闭虚拟内存或者向扩大， 要先disable

swapoff /swapfile1