swap分区扩展

swap分区的作用：swap分区是在系统的物理内存不够用时，把硬盘空间中的一部分空间释放出来，以供当前运行的程序使用的。

磁盘分配

第一步（创建分区）

[root@bogon ~]# gdisk /dev/sdb

GPT fdisk (gdisk) version 0.8.10

Partition table scan:

  MBR: protective

  BSD: not present

  APM: not present

  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): n

Partition number (2-128, default 2):

First sector (34-41943006, default = 10487808) or {+-}size{KMGTP}:

Last sector (10487808-41943006, default = 41943006) or {+-}size{KMGTP}: +5G

Current type is ‘Linux filesystem‘

Hex code or GUID (L to show codes, Enter = 8300):

Changed type of partition to ‘Linux filesystem‘

Command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING

PARTITIONS!!

Do you want to proceed? (Y/N): y

OK; writing new GUID partition table (GPT) to /dev/sdb.

Warning: The kernel is still using the old partition table.

The new table will be used at the next reboot.

The operation has completed successfully.

第二步（格式化swap）

加载新分区

[root@bogon ~]# partx -a /dev/sdb

partx: /dev/sdb: error adding partition 1

格式化swap分区

[root@bogon ~]# mkswap  /dev/sdb2

Setting up swapspace version 1, size = 5242876 KiB

no label, UUID=8d003c6d-43d1-4e51-ab4a-bf60df5e4c9b

第三步（添加空间）

查看原有swap大小

[root@bogon ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:         7803         445        6964          16         393        7057

Swap:          5119           0        5119

将磁盘空间加入swap

[root@bogon ~]# swapon /dev/sdb2

查看现有swap大小

[root@bogon ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:         7803         449        6959          16         393        7052

Swap:         10239           0       10239

查看swap分区用到的磁盘

[root@bogon ~]# swapon -s

Filename                                Type            Size    Used    Priority

/dev/sda2                               partition       5242876 0       -2

/dev/sdb2                               partition       5242876 0       -3

[root@bogon ~]#

删除空间

[root@bogon ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:           7803         449        6960          16         393        7053

Swap:         10239           0       10239

[root@bogon ~]# swapoff /dev/sdb2

[root@bogon ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:           7803         445        6963          16         393        7056

Swap:          5119           0        5119

[root@bogon ~]#

文件分配

[root@bogon ~]# dd if=/dev/zero of=swap_file bs=1M count=500

500+0 records in

500+0 records out

524288000 bytes (524 MB) copied, 0.467293 s, 1.1 GB/s

[root@bogon ~]# ll /root/swap_file

-rw-r--r-- 1 root root 524288000 Dec  6 18:07 /root/swap_file

[root@bogon ~]# chmod 0600 /root/swap_file

[root@bogon ~]# mkswap -f /root/swap_file

Setting up swapspace version 1, size = 511996 KiB

no label, UUID=78e51afa-9ec8-483b-9be8-af83c212daf8

[root@bogon ~]# swapon /root/swap_file

[root@bogon ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:           7803         445        6449          16         907        7049

Swap:          5619           0        5619

[root@bogon ~]# swapon -s

Filename                                Type            Size    Used    Priority

/dev/sda2                               partition       5242876 0       -2

/root/swap_file                         file    511996  0       -3

38.swap分区扩展

原文：https://www.cnblogs.com/ai-fei-ai/p/14216014.html