linux增加swap分区和删除swapfile文件的方法

 

 

创建swapfile文件

执行命令：dd if=/dev/zero of=swapfile bs=1024 count=5000000
注：可根据实际需要更改count值的大小，这里设置5000000，大概就是4G多

 

 

[root@node2 var]# dd if=/dev/zero of=swapfile bs=1024 count=500000
500000+0 records in
500000+0 records out
512000000 bytes (512 MB) copied, 5.92783 s, 86.4 MB/s
[root@node2 var]# ls -alh
total 489M
drwxr-xr-x. 19 root root  283 May  9 13:21 .
dr-xr-xr-x. 20 root root  269 Apr  1 09:47 ..
drwxr-xr-x.  2 root root    6 Apr 11  2018 adm
drwxr-xr-x.  5 root root   44 Jan  7 19:37 cache
drwxr-xr-x.  2 root root    6 Aug  8  2019 crash
drwxr-xr-x.  3 root root   34 Mar  2 16:10 db
drwxr-xr-x.  3 root root   18 Jan  7 19:37 empty
drwxr-xr-x.  2 root root    6 Apr 11  2018 games
drwxr-xr-x.  2 root root    6 Apr 11  2018 gopher
drwxr-xr-x.  3 root root   18 Sep 14  2019 kerberos
drwxr-xr-x. 34 root root 4.0K Apr 20 11:39 lib
drwxr-xr-x.  2 root root    6 Apr 11  2018 local
lrwxrwxrwx.  1 root root   11 Jan  7 19:37 lock -> ../run/lock
drwxr-xr-x. 10 root root 4.0K May  9 13:11 log
lrwxrwxrwx.  1 root root   10 Jan  7 19:37 mail -> spool/mail
drwxr-xr-x.  2 root root    6 Apr 11  2018 nis
drwxr-xr-x.  2 root root    6 Apr 11  2018 opt
drwxr-xr-x.  2 root root    6 Apr 11  2018 preserve
lrwxrwxrwx.  1 root root    6 Jan  7 19:37 run -> ../run
drwxr-xr-x.  8 root root   87 Jan  7 19:37 spool
-rw-r--r--   1 root root 489M May  9 13:21 swapfile
drwxrwxrwt.  4 root root  112 May  9 13:11 tmp
-rw-r--r--.  1 root root  163 Jan  7 19:37 .updated
drwxr-xr-x.  2 root root    6 Apr 11  2018 yp
[root@node2 var]# free -h
              total        used        free      shared  buff/cache   available
Mem:           1.8G        495M        186M        9.5M        1.1G        1.1G
Swap:          3.9G          0B        3.9G 

将swapfile设置为swap空间

执行命令：mkswap swapfile

[root@node2 var]# mkswap swapfile
Setting up swapspace version 1, size = 499996 KiB
no label, UUID=c67544b9-60b6-426e-8349-5f62813d9deb
[root@node2 var]# free -h
              total        used        free      shared  buff/cache   available
Mem:           1.8G        497M        180M        9.6M        1.1G        1.1G
Swap:          3.9G          0B        3.9G

启用交换空间

执行命令：swapon swapfile

[root@node2 var]# swapon swapfile
swapon: /var/swapfile: insecure permissions 0644, 0600 suggested.

[root@node2 var]# free -h
              total        used        free      shared  buff/cache   available
Mem:           1.8G        497M        180M        9.6M        1.1G        1.1G
Swap:          4.4G          0B        4.4G   #将489M的交换文件的空间启用了

删除swapfile

如果创建了swapfile之后，想要删除，必须先执行以下命令
swapoff swapfile

[root@node2 var]# swapoff swapfile
[root@node2 var]# free -h
              total        used        free      shared  buff/cache   available
Mem:           1.8G        497M        180M        9.6M        1.1G        1.1G
Swap:          3.9G          0B        3.9G

然后再执行删除文件操作
rm swapfile

[root@node2 var]# rm swapfile
rm: remove regular file ‘swapfile’? y
[root@node2 var]# ls -alh
total 12K
drwxr-xr-x. 19 root root  267 May  9 14:15 .
dr-xr-xr-x. 20 root root  269 Apr  1 09:47 ..
drwxr-xr-x.  2 root root    6 Apr 11  2018 adm
drwxr-xr-x.  5 root root   44 Jan  7 19:37 cache
drwxr-xr-x.  2 root root    6 Aug  8  2019 crash
drwxr-xr-x.  3 root root   34 Mar  2 16:10 db
drwxr-xr-x.  3 root root   18 Jan  7 19:37 empty
drwxr-xr-x.  2 root root    6 Apr 11  2018 games
drwxr-xr-x.  2 root root    6 Apr 11  2018 gopher
drwxr-xr-x.  3 root root   18 Sep 14  2019 kerberos
drwxr-xr-x. 34 root root 4.0K Apr 20 11:39 lib
drwxr-xr-x.  2 root root    6 Apr 11  2018 local
lrwxrwxrwx.  1 root root   11 Jan  7 19:37 lock -> ../run/lock
drwxr-xr-x. 10 root root 4.0K May  9 13:11 log
lrwxrwxrwx.  1 root root   10 Jan  7 19:37 mail -> spool/mail
drwxr-xr-x.  2 root root    6 Apr 11  2018 nis
drwxr-xr-x.  2 root root    6 Apr 11  2018 opt
drwxr-xr-x.  2 root root    6 Apr 11  2018 preserve
lrwxrwxrwx.  1 root root    6 Jan  7 19:37 run -> ../run
drwxr-xr-x.  8 root root   87 Jan  7 19:37 spool
drwxrwxrwt.  4 root root  112 May  9 13:11 tmp
-rw-r--r--.  1 root root  163 Jan  7 19:37 .updated
drwxr-xr-x.  2 root root    6 Apr 11  2018 yp
[root@node2 var]# 

 

注：如果没有执行swapoff操作，就执行执行删除文件的操作，系统会报错，不给删除。swapoff相当于是卸载swap分区。