Linux扩充虚拟内存（swap）

虚拟内存swap一般设置为物理内存的2倍即可，多了也是浪费硬盘。

(base) [mca@clu08 bin]$ free -m
              total        used        free      shared  buff/cache   available
Mem:           7809        5995         954          11         859        1496
Swap:          6143         465        5678
# 使用root用户操作
(base) [mca@clu08 bin]$ su -
Password: 
Last login: Fri Dec  3 17:14:49 CST 2021 on pts/8
Last failed login: Mon Dec  6 14:43:33 CST 2021 from 10.0.9.118 on ssh:notty
There were 2 failed login attempts since the last successful login.

# count的值为实际想要的内存，一般设置为物理内存的2倍
[root@clu08 ~]# dd if=/dev/zero of=/root/swapfile2 bs=1M count=16383
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB) copied, 108.758 s, 98.7 MB/s
[root@clu08 ~]# chmod 0600 /root/swapfile2
[root@clu08 ~]# mkswap /root/swapfile2
Setting up swapspace version 1, size = 10485756 KiB
no label, UUID=365528fa-cc2f-4d7a-a7c5-e726c7d6956e
[root@clu08 ~]# swapon /root/swapfile2

# 再次查看，虚拟内存得到扩充
[root@clu08 ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           7809        5919         188          11        1701        1564
Swap:         16383         465       15918