Ubuntu 22.04 设置swap交换空间

经常爆内存，导致很多应用没有办法一直正常运行，可以通过设置swap来缓解一下，虽然和内存的速度无法媲美，但是能一定程度缓解一下问题。

一、查看当前分区

查看当前系统的swap大小

free -m

二、关闭现有的swap分区

将/etc/fstab文件中所有设置为swap的设备关闭，然后才能创建swap

sudo swapoff -a

三、创建新的swap文件

bs×count=最后生成的swap大小，这里设置8G

sudo dd if=/dev/zero of=/swapfile bs=1G count=8

四、设置权限

出于安全原因，交换文件应该只能被root用户读写

sudo chmod 600 /swapfile

 五、设置swap

sudo mkswap /swapfile

 六、启用swap

sudo swapon /swapfile

七、设置swap永久有效

编辑 sudo vim /etc/fstab 将下面内容添加到最后一行

/swapfile swap swap sw 0 0

全程操作记录

root@ubuntu:/# free -h
              total        used        free      shared  buff/cache   available
Mem:           23Gi        22Gi       203Mi       1.0Mi       777Mi       580Mi
Swap:            0B          0B          0B
root@ubuntu:/#
root@ubuntu:/# sudo dd if=/dev/zero of=/swapfile bs=1G count=8
8+0 records in
8+0 records out
8589934592 bytes (8.6 GB, 8.0 GiB) copied, 8.14848 s, 1.1 GB/s
root@ubuntu:/# sudo chmod 600 /swapfile
root@ubuntu:/# sudo mkswap /swapfile
Setting up swapspace version 1, size = 8 GiB (8589930496 bytes)
no label, UUID=7bab5b72-8602-4094-9211-622de895302d
root@ubuntu:/# sudo swapon /swapfile
root@ubuntu:/# sudo vim /etc/fstab
root@ubuntu:/# 
root@ubuntu:/# cat /etc/fstab 
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
#                
# / was on /dev/ubuntu-vg/ubuntu-lv during curtin installation
/dev/disk/by-id/dm-uuid-LVM-L8iEhDkz0j7XOkZNxq1vqTybkF7AD0mbDMftF69chzey1qdN3t7jrCDJ1egzu2BE / ext4 defaults 0 1
# /boot was on /dev/sda2 during curtin installation
/dev/disk/by-uuid/ff68fd53-d03e-4dbe-91e1-414c0776da12 /boot ext4 defaults 0 1
/dev/mapper/ubuntu--vg2-database  /database  ext4 defaults 0 0
# swap
/swapfile swap swap sw 0 0
root@ubuntu:/# 
root@ubuntu:/# free -h
              total        used        free      shared  buff/cache   available
Mem:           23Gi       4.5Gi       7.2Gi       1.0Mi        11Gi        18Gi
Swap:         8.0Gi          0B       8.0Gi
root@ubuntu:/#