上次在aws上创建了一服务器，但是用free命令查看时发现swap为0,决定添加上交换文件

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             total       used       free     shared    buffers     cached
Mem:       1019452     419436     600016        104      14824      96564
-/+ buffers/cache:     308048     711404
Swap:            0          0          0

首先登陆服务器并切换成root用户

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       __|  __|_  )
       _|  (     /   Amazon Linux AMI
      ___|\___|___|

https://aws.amazon.com/amazon-linux-ami/2015.09-release-notes/
 su - //su -s

  1. 利用dd命令创建存储文件,这里我们创建一个512M的文件足矣 

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    # dd if=/dev/zero of=/swapfile1 bs=1024 count=524288
    524288+0 records in
    524288+0 records out
    536870912 bytes (537 MB) copied, 3.23347 s, 166 MB/s

    > if=/dev/zero : Read from /dev/zero file. /dev/zero is a special file in that provides as many null characters to build storage file called /swapfile1.
    > of=/swapfile1 : Read from /dev/zero write storage file to /swapfile1.
    > bs=1024 : Read and write 1024 BYTES bytes at a time.
    > count=524288 : Copy only 523288 BLOCKS input blocks.

  2. 分配swapfile1权限

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    # chown root:root /swapfile1
    # chmod 0600 /swapfile1

  3. 建立一个交换区

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    # mkswap /swapfile1

    > Setting up swapspace version 1, size = 524284 KiB
    > no label, UUID=0e5e7c60-bbba-4089-a76c-2bb29c0f0839

  4. 开启交换文件

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    # swapon /swapfile1

  5. 启动时挂载

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    # vi /etc/fstab
    /swapfile1 none swap sw 0 0

再来free看一看

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             total       used       free     shared    buffers     cached
Mem:       1019452     419436     600016        104      14824      96564
-/+ buffers/cache:     308048     711404
Swap:       524284          0     524284
参考