Slave of no one
Authors of redis have their hearts in the right place.
Here is what they say about master-slave terminology which is used quite often throughout the industry:
A note about slavery: it's unfortunate that originally the master-slave terminology was picked for databases. When Redis was designed the existing terminology was used without much analysis of alternatives, however a SLAVEOF NO ONE command was added as a freedom message. Instead of changing the terminology, that would require breaking backward compatible in the API and INFO output, we want to use this page to remember you about slavery, a crime against humanity now but something that was perpetuated throughout the whole human history.
If slavery is not wrong, nothing is wrong. – Abraham Lincoln