---
title: "阿里云ecs添加swap"
date: 2021-10-18T16:59:28+08:00
draft: false
---

查看当前是没有swap的

 

```bash
$ free -m

​       total    used    free   shared  buffers   cached

Mem:      498    310    187     0     17    170

-/+ buffers/cache:    122    375

Swap:      0     0     0




$ sudo df -hT

Filesystem   Type  Size Used Avail Use% Mounted on

/dev/xvda1   ext4  20G 3.7G  16G 20% /

tmpfs     tmpfs 250M   0 250M  0% /dev/shm
```



 



 

我们将swap挂载到/var下

 

$ sudo dd if=/dev/zero of=/var/swap bs=1M count=2048

2048+0 records in

2048+0 records out

2147483648 bytes (2.1 GB) copied, 47.8375 s, 44.9 MB/s

 

 

$ sudo mkswap /var/swap

 

$ sudo chmod 0600 /var/swap

 

$ sudo swapon /var/swap

 

挂载完毕后，查看内存使用情况。发现swap出现了。

 

[root@iZ23zvh0w6mZ lnmp1.1-full]# free -m

​       total    used    free   shared  buffers   cached

Mem:      498    456     41     0     10    100

-/+ buffers/cache:    346    152

Swap:     2047     0    2047

 

 

ok，swap已经可以使用了，接下来我们要将swap开机自动挂载。

编辑/etc/fstab文件

 

$ sudo vi /etc/fstab

\#

\# /etc/fstab

\# Created by anaconda on Mon Aug 11 16:27:41 2014

\#

\# Accessible filesystems, by reference, are maintained under '/dev/disk'

\# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

\#

UUID=e76a7b8d-20c2-4f94-bdd1-f4054a34c206 / ext4 defaults,barrier=0 1 1

tmpfs          /dev/shm        tmpfs  defaults    0 0

devpts         /dev/pts        devpts gid=5,mode=620 0 0

sysfs          /sys          sysfs  defaults    0 0

proc          /proc          proc  defaults    0 0

none         /proc/xen        xenfs  defaults    0 0

/var/swap        swap          swap  defaults    0 0

因为阿里云默认是不让用户使用swap的（貌似现在的系统模版更新了，这一行新装系统都没有了，如果没有请忽略此步。）。

编辑/etc/rc.d/rc.local文件，将文件中的swapoff行注释或删掉。

 

$ sudo vi /etc/rc.d/rc.local 

\#!/bin/sh

\#

\# This script will be executed *after* all the other init scripts.

\# You can put your own initialization stuff in here if you don't

\# want to do the full Sys V style init stuff.

 

touch /var/lock/subsys/local

ulimit -SHn 65535

\#swapoff -a //加上"#"号注释掉或者直接删除