linux 创建swap分区

1.查看SWAP
[root@192 oc]# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/sda3                               partition       8024    104     -1
[root@192 oc]#
 
2.通过DD创建文件


 dd if=/dev/zero of=/swapfile bs=512 count=4000000


 dd if=/dev/zero of=/swapfile bs=512 count=8000000
2000000+0 records in
2000000+0 records out
1024000000 bytes (1.0 GB) copied, 23.4213 seconds, 43.7 MB/s
[root@192 oc]#
[root@192 oc]# ll
总计 1001012
drwx------ 2 root root      16384 06-03 06:56 lost+found
-rw-r--r-- 1 root root 1024000000 06-12 10:24 swap
drwxr-xr-x 4 root root       4096 06-08 16:15 tmp
[root@192 oc]#

3.转化为swap格式
[root@backoffice01 ~]# mkswap /swapfile
mkswap: /swapfile: warning: don't erase bootbits sectors
        on whole disk. Use -f to force.
Setting up swapspace version 1, size = 1999996 KiB
no label, UUID=92896c21-e21b-4e16-b5de-9319931b31ac


[root@192 oc]# free
             total       used       free     shared    buffers     cached
Mem:       1035108    1018168      16940          0      14716     892500
-/+ buffers/cache:     110952     924156
Swap:         8024        104       7920
[root@192 oc]#

启用，加入到swap池中。
[root@192 oc]# swapon  /swapfile
[root@192 oc]# free
             total       used       free     shared    buffers     cached
Mem:       1035108    1018228      16880          0      14748     892592
-/+ buffers/cache:     110888     924220
Swap:      1008016        104    1007912
[root@192 oc]#
 
[root@192 oc]# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/sda3                               partition       8024    104     -1
/oc/swap                                file            999992  0       -4
[root@192 oc]#
 
从swap池中拿掉
[root@192 oc]# swapoff /oc/swap
[root@192 oc]# free
             total       used       free     shared    buffers     cached
Mem:       1035108    1018780      16328          0      15096     892760
-/+ buffers/cache:     110924     924184
Swap:         8024        104       7920
[root@192 oc]# cat /proc/swaps
Filename                                Type            Size    Used    Priority
/dev/sda3                               partition       8024    104     -1
[root@192 oc]#
 
开机自动启动：
/swapfile               swap                    swap    defaults        0 0
 
另：
将整个设备划为swap分区
fdisk时代码为82 linux swap，
分区后：
# mkswap /dev/sdc3
# swapon /dev/sdc3