Postrgres

systemctl enable postgresql-11
systemctl edit postgresql-11.service 
edit by putting these lines:
[Service]
Environment=PGDATA=/diska/pgsql/11.9/data
systemctl daemon-reload
systemctl start postgresql-11
[root@fndcatemp2 data]# ps auxwww | grep postma 
postgres  3531  0.3  0.6 9117360 451648 ?      Ss   11:14   0:00 /usr/pgsql-11/bin/postmaster -D /diska/pgsql/11.9/data
root      4780  0.0  0.0 112816   976 pts/0    S+   11:16   0:00 grep --color=auto postma

Drop caches:

sysctl -w vm.drop_caches=3 

Useful metaqueries

https://gist.github.com/rgreenjr/3637525