One challenge is with Exadata cells in a lab environment is that they are secure! This means that it has long lock out times in the event of an incorrect login and tough lock settings. You can manually change these.. but every time you update your cell there is a chance they will be reset.
A more permanent way is to use /opt/oracle.cellos/host_access_control on each storage cell. https://docs.oracle.com/cd/E58626_01/html/E58630/z40036a01393423.html#scrolltoc
For example, if you want to drop the lock time in the event of a failed login from 10 minutes to a more manageable 60 seconds you would issue the command
/opt/oracle.cellos/host_access_control pam-auth --lock=60
You can combine multiple pam-auth commands on the same line.. e.g. if I also want to say that the cell only remembers one previous password I could say
/opt/oracle.cellos/host_access_control pam-auth --lock=60 --remember=1
There are a lot of options for this tool – you can set the system back to secure defaults, or make it even more secure, such as locking an account after a single failed login!