When switching users with Su, the user is not available at present

[root@iZ28kbs8yb3Z ~]# su - redis
This account is currently not available.

The reason is that redis users are set to disable shell login

[root@iZ28kbs8yb3Z ~]# cat /etc/passwd|grep redis
redis:x:497:498:Redis Server:/var/lib/redis:/sbin/nologin

Use root to modify passwd file and delete/SBIN/nologin