利用文件来扩展交换分区，增减了灵活性，这种方法适用于硬盘中没有可分区的剩余空间，充分利用硬盘中的文件来提高系统的性能，也可以将文件拷贝到其它主机中使用。

扩充swap交换分区

新建swap交换文件

[root@localhost ~]# dd if=/dev/dd if=/dev/zero of=swapfile bs=1M count=1024       

1024+0 records in

1024+0 records out

1073741824 bytes (1.1 GB) copied, 7.34123 s, 146 MB/s

[root@localhost ~]# ls -lh /root/swapfile

-rw-r--r--. 1 root root 1.0G Aug 31 09:50 /root/swapfile

[root@localhost ~]# mkswap /root/swapfile

Setting up swapspace version 1, size = 1048572 KiB

no label, UUID=b9990096-d55f-414d-a7e7-b16097af7088

修改fstab配置

[root@localhost ~]# vi /etc/fstab

#

# /etc/fstab

# Created by anaconda on Thu Jul 21 11:23:38 2016

#

# 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=80371af2-ee0e-481c-b71a-c9d25b11800a /          xfs     defaults        0 0

UUID=33974954-468b-490d-b84a-c955716d7146 /boot          xfs     defaults        0 0

UUID=346923cc-58f2-44b6-91d0-6ad8687ebd7b /testdir      xfs     defaults        0 0

UUID=981b1be0-81ec-46aa-bb2c-6d7f0d79aa46 swap             swap    defaults        0 0

/root/swapfile  swap    swap    defaults    pri=1000   0

挂载文件

[root@localhost ~]# swapon -s

Filename                    Type            Size    Used    Priority

/dev/sda2                    partition       3905532 0       -1

[root@localhost ~]# swapon -a   #挂载时会报一个权限错误，需要将swapfile文件的权限修改为600

swapon: /root/swapfile: insecure permissions 0644, 0600 suggested.

[root@localhost ~]# swapon -s

Filename                 Type            Size       Used    Priority

/dev/sda2                 partition       3905532 0      -1

/root/swapfile              file           1048572 0     100

删除swap分区

取消激活swap分区

[root@localhost ~]# swapoff /root/swapfile

[root@localhost ~]# swapon -s

Filename                                Type            Size    Used    Priority

/dev/sda2                               partition       3905532 0       -1

删除配置信息

[root@localhost ~]# vi /etc/fstab

#

# /etc/fstab

# Created by anaconda on Thu Jul 21 11:23:38 2016

#

# 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=80371af2-ee0e-481c-b71a-c9d25b11800a /          xfs     defaults        0 0

UUID=33974954-468b-490d-b84a-c955716d7146 /boot          xfs     defaults        0 0

UUID=346923cc-58f2-44b6-91d0-6ad8687ebd7b /testdir      xfs     defaults        0 0

UUID=981b1be0-81ec-46aa-bb2c-6d7f0d79aa46 swap             swap    defaults        0 0

/root/swapfile  swap    swap    defaults    pri=1000   0    #删除该行

删除文件

[root@localhost ~]# rm -f /root/swapfile 

本文出自 “Linux路上” 博客，请务必保留此出处http://dreamlinuxc.blog.51cto.com/5733156/1844624

利用文件来扩展swap交换分区空间