Out Of Place patching - swap prerequisite failure

Problem:

Oracle Out Of Place patching may fail with the following error:

[root@rac1 29708703]# export ORACLE_HOME=/u01/app/19.3.0/grid
[root@rac1 29708703]# $ORACLE_HOME/OPatch/opatchauto apply -oh $ORACLE_HOME -outofplace
...
---------------------------Patching Failed---------------------------------
Checking swap space: 0 MB available, 500 MB required.    Failed <<<<

Cause:

FlashGrid cluster has swap disabled by design. This prevents cluster brown-outs in case of low memory. However, some Oracle utilities still check for swap enabled for historical reasons.

Solution:

1. Create a temporary 500MB swapfile:

# dd if=/dev/zero of=/swapfile bs=1024k count=500 oflag=direct
# chown root:root /swapfile
# chmod 600 /swapfile
# mkswap  /swapfile
# swapon /swapfile

2. Resume patching:

# $ORACLE_HOME/OPatch/opatchauto resume

3. Remove swapfile

# swapoff /swapfile
# rm -rf /swapfile