Linux 之 swap分区创建与管理

Posted 2020-11-05

swap分区创建与管理

1.查看swap分区

[[email protected] ~]# free -h
                         total       used       free     shared    buffers     cached
Mem:          2.0G       1.0G       944M       1.5M       265M       341M
-/+ buffers/cache:       454M       1.5G
Swap:         4.0G         0B       4.0G           #swap分区大小
[[email protected] ~]# fdisk -l

Disk /dev/sda: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0004c723

     Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26         548     4194304   82  Linux swap / Solaris   #swap挂载地方
Partition 2 does not end on cylinder boundary.
/dev/sda3             548        6528    48028672   83  Linux

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2.关闭开启swap

[[email protected] ~]# swapoff /dev/sda2
[[email protected] ~]# free -h
                         total       used       free     shared    buffers     cached
Mem:          2.0G       1.1G       923M       1.5M       265M       341M
-/+ buffers/cache:       475M       1.5G
Swap:           0B         0B         0B
[[email protected] ~]# swapon /dev/sda2 
[[email protected] ~]# free -h
                         total       used       free     shared    buffers     cached
Mem:          2.0G       1.0G       944M       1.5M       265M       341M
-/+ buffers/cache:       455M       1.5G
Swap:         4.0G         0B       4.0G

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3.swap分区扩容

[[email protected] ~]# dd if=/dev/zero of=/opt/swapfile bs=1M count=1024      #创建一个swap分区
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 19.2751 s, 55.7 MB/s
[[email protected] ~]# mkswap /opt/swapfile                #格式化成swap格式
mkswap: /opt/swapfile: warning: don‘t erase bootbits sectors
                on whole disk. Use -f to force.
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=565ba456-ae47-4749-a7f7-1cd26f37bdbd
[[email protected] ~]# swapon /opt/swapfile               #启用该swap分区，并会自动合并到原来的swap分区上
[[email protected] ~]# free -h
                         total       used       free     shared    buffers     cached
Mem:          2.0G       1.9G       101M       1.5M       264M       1.1G
-/+ buffers/cache:       466M       1.5G
Swap:         5.0G         0B       5.0G