文档课题：增加swap空间大小

以下为swap由8g增加到9g的演练过程：

1、当前swap大小

[root@dbserver ~]# lsblk

NAME          MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT

sda             8:0    0  100G  0 disk

├─sda1          8:1    0    2G  0 part /boot

└─sda2          8:2    0   98G  0 part

  ├─rhel-root 253:0    0   55G  0 lvm  /

  ├─rhel-swap 253:1    0    8G  0 lvm  [SWAP]

  └─rhel-home 253:2    0   35G  0 lvm  /home

sr0            11:0    1 1024M  0 rom 

[root@dbserver ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:           7821         818        6362          26         640        6687

Swap:          8191           0        8191

[root@dbserver ~]# swapon -s

Filename                                Type            Size    Used    Priority

/dev/dm-1                               partition    8388604 0       -2

2、扩展swap分区

2.1、新磁盘方式

添加一块1g磁盘，并完成分区.

[root@dbserver ~]# lsblk -p

NAME                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT

/dev/sda                    8:0    0  100G  0 disk

├─/dev/sda1                 8:1    0    2G  0 part /boot

└─/dev/sda2                 8:2    0   98G  0 part

  ├─/dev/mapper/rhel-root 253:0    0   55G  0 lvm  /

  ├─/dev/mapper/rhel-swap 253:1    0    8G  0 lvm  [SWAP]

  └─/dev/mapper/rhel-home 253:2    0   35G  0 lvm  /home

/dev/sdb                    8:16   0    1G  0 disk

└─/dev/sdb1                 8:17   0 1023M  0 part

/dev/sr0                   11:0    1 1024M  0 rom

说明：/dev/sdb1为新加磁盘分区

#将新加分区设置为交换区.

[root@dbserver ~]# mkswap /dev/sdb1

Setting up swapspace version 1, size = 1047548 KiB

no label, UUID=cce40e01-b659-43aa-8801-a2a0cccf77eb

#启用交换分区/dev/sdb1

[root@dbserver ~]# swapon /dev/sdb1

[root@dbserver ~]# swapon -s

Filename                                Type            Size    Used    Priority

/dev/dm-1                               partition       8388604 0       -2

/dev/sdb1                               partition       1047548 0       -3

[root@dbserver ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:           7821         581        6770          15         469        6946

Swap:          9214           0        9214

#设置开机自动挂载

[root@dbserver ~]# echo "/dev/sdb1 swap swap defaults 0 0" >> /etc/fstab

说明：第一个0表示不要备份，第二0表示系统开机过程中不需要检验.

2.2、dd方式

dd方式增加swap空间.

[root@dbserver ~]# dd if=/dev/zero of=/swap01 bs=1024 count=1048572      #创建大小为1024m的文件

1048572+0 records in

1048572+0 records out

1073737728 bytes (1.1 GB) copied, 11.7121 s, 91.7 MB/s

说明：

bs=bytes：同时设置读入/输出的块大小为bytes个字节

count=blocks：仅拷贝blocks个块，块大小等于bs指定的字节数

[root@dbserver ~]# mkswap /swap01

Setting up swapspace version 1, size = 1048568 KiB

no label, UUID=6d8a5cb5-2fb7-4bcf-acff-5eae904dc325

[root@dbserver ~]# swapon /swap01

swapon: /swap01: insecure permissions 0644, 0600 suggested.

[root@dbserver ~]# free -m

              total        used        free      shared  buff/cache   available

Mem:           7821         851        5276          26        1693        6640

Swap:         10238           0       10238

[root@dbserver ~]# swapon -s

Filename                                Type            Size    Used    Priority

/dev/sdb1                               partition       1047548 0       -2

/dev/dm-1                               partition       8388604 0       -3

/swap01                                 file    1048568 0       -4

[root@dbserver ~]# echo "/swap01 swap swap defaults 0 0" >> /etc/fstab

[root@dbserver ~]# cat /etc/fstab

 

#

# /etc/fstab

# Created by anaconda on Thu Nov 25 20:55:05 2021

#

# 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

#

/dev/mapper/rhel-root   /                       xfs     defaults        0 0

UUID=d2c7f75a-b3f7-46b1-84bc-56e40c0c4c5d /boot                   xfs     defaults        0 0

/dev/mapper/rhel-home   /home                   xfs     defaults        0 0

/dev/mapper/rhel-swap   swap                    swap    defaults        0 0

/dev/sdb1 swap swap defaults 0 0

/swap01 swap swap defaults 0 0

 

说明：不挂载swap用swapoff /swap01.