阿里云ECS镜象默认未创建交换分区SWAP导致应用内存不够出现异常

阿里云环境数据宕机了。

SQL> connect / as sysdba
Connected to an idle instance.
SQL> show parameter sga
ORA-01034: ORACLE not available
Process ID: 0
Session ID: 0 Serial number: 0


SQL> shutdown immediate
ORA-01034: ORACLE not available
ORA-27102: out of memory
Linux-x86_64 Error: 12: Cannot allocate memory
Additional information: 26
Additional information: 23
Additional information: 1660944384

看内存发现swap没了

[[email protected] ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           7820        2654         142        3245        5023        1637
Swap:             0           0           0

[[email protected]]# dd if=/dev/zero of=/swapfile bs=1024 count=4194304
4194304+0 records in
4194304+0 records out
4294967296 bytes (4.3 GB) copied, 25.8686 s, 166 MB/s
[[email protected]]# mkswap /swapfile 
Setting up swapspace version 1, size = 4194300 KiB
no label, UUID=f0d30855-a3a0-4b09-85ff-f5a393059382
[[email protected]]# swapon /swapfile 
swapon: /swapfile: insecure permissions 0644, 0600 suggested.
[[email protected] ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:           7.6G        1.9G        465M        3.2G        5.2G        2.2G
Swap:          4.0G          0B        4.0G

为什么交换分区没有？经分析是采用的阿里镜像快速安装的操作系统，没有交换分区。
按8G以上，按8G设交换分区，8G以下按实际物理内存设置交换分区。
对其他所有阿里云机器批量修改

[[email protected] ~]#  free -h
              total        used        free      shared  buff/cache   available
Mem:            15G        960M        5.3G        692K        9.3G         14G
Swap:            0B          0B          0B
[[email protected] ~]#  dd if=/dev/zero of=/swapfile bs=1024 count=8388608
8388608+0 records in
8388608+0 records out
8589934592 bytes (8.6 GB) copied, 38.701 s, 222 MB/s
[[email protected] ~]#  mkswap /swapfile 
Setting up swapspace version 1, size = 8388604 KiB
no label, UUID=65fd6266-3f89-4ada-931e-45d51c95e3e1
[[email protected] ~]#  swapon /swapfile
swapon: /swapfile: insecure permissions 0644, 0600 suggested.
[[email protected] ~]#  free -h
              total        used        free      shared  buff/cache   available
Mem:            15G        967M        174M        692K         14G         14G
Swap:          8.0G          0B        8.0G

为了确认下次开机自动打开SWAP

[[email protected] ~]# vi /etc/fstab
/swapfile	swap	swap	default	0	0
[[email protected] ~]#