Linux创建Swap命令

简介

手里有几台小鸡，安装某些服务内存不够，所以就扩大swap分区。本次实验均使用dd命令

本次实验环境

序号	环境	版本	内存(M)
1	Ubuntu16.04 minimal	4.4.0-109-generic	512
2	Ubuntu16.04	4.4.0-130-generic	1024

1.创建文件

我这里都是创建内存的两倍

root@VM-16-13-ubuntu:~# sudo dd if=/dev/zero of=/swapspace bs=1G count=2
dd: memory exhausted by input buffer of size 1073741824 bytes (1.0 GiB)
root@VM-16-13-ubuntu:~# du /swapspace
0       /swapspace
root@VM-16-13-ubuntu:~# free -h
              total        used        free      shared  buff/cache   available
Mem:           864M         90M        653M        9.4M        119M        636M
Swap:            0B          0B          0B

*bs不能超过可用内存。**dd: memory exhausted by input buffer of size 1073741824 bytes (1.0 GiB)*

root@VM-16-13-ubuntu:~# sudo dd if=/dev/zero of=/swapspace bs=636M count=2
2+0 records in
2+0 records out
1333788672 bytes (1.3 GB, 1.2 GiB) copied, 12.8161 s, 104 MB/s
root@VM-16-13-ubuntu:~# du /swapspace
1302532 /swapspace

2.设置权限

sudo chmod 600 /swapspace

3.设置启动Linux交换区

root@VM-16-13-ubuntu:~# sudo mkswap /swapspace
Setting up swapspace version 1, size = 2 GiB (2097147904 bytes)
no label, UUID=c8861fd4-f125-4d6f-abad-8854079fec5c
root@VM-16-13-ubuntu:~# sudo swapon /swapspace
root@VM-16-13-ubuntu:~# free -h
              total        used        free      shared  buff/cache   available
Mem:           864M         92M        665M        9.4M        106M        641M
Swap:          2.0G          0B        2.0G

写入/etc/fstab文件

root@VM-16-13-ubuntu:~# cat /etc/fstab
/dev/vda1            /                    ext4       noatime,acl,user_xattr 1 1
proc                 /proc                proc       defaults              0 0
sysfs                /sys                 sysfs      noauto                0 0
debugfs              /sys/kernel/debug    debugfs    noauto                0 0
devpts               /dev/pts             devpts     mode=0620,gid=5       0 0
root@VM-16-13-ubuntu:~# echo "/swapspace swap swap defaults    0  0" >> /etc/fstab
root@VM-16-13-ubuntu:~# cat /etc/fstab
/dev/vda1            /                    ext4       noatime,acl,user_xattr 1 1
proc                 /proc                proc       defaults              0 0
sysfs                /sys                 sysfs      noauto                0 0
debugfs              /sys/kernel/debug    debugfs    noauto                0 0
devpts               /dev/pts             devpts     mode=0620,gid=5       0 0
/swapspace swap swap defaults    0  0

echo "/swapspace swap swap defaults    0  0" >> /etc/fstab
或
vim /etc/fstab手动添加进去

总结

sudo dd if=/dev/zero of=/{filename}.swap bs=1M count={swap_size}
sudo chmod 600 /{filename}.swap
sudo mkswap /{filename}.swap
sudo swapon /{filename}.swap
echo “/{filename}.swap swap swap defaults 0 0” >> /etc/fstab

sudo dd if=/dev/zero of=/{filename}.swap bs=1M count={swap_size} 
sudo chmod 600 /{filename}.swap
sudo mkswap /{filename}.swap
sudo swapon /{filename}.swap
echo "/{filename}.swap    swap    swap    defaults    0    0" >> /etc/fstab

参考链接：