redisSlaveOf(host, port)The redisSlaveOf command can change the replication settings of a slave on the fly. If a Redis server is arleady acting as slave, the function redisSlaveOf(host="no",port="one") will turn off the replicaiton turning the Redis server into a MASTER. In the proper form redisSlaveOf(hostname,port) will make the server a slave of the specific server listening at the specified hostname and port.
If a server is already a slave of some master, redisSlaveOf(hostname,port )will stop the replication against the old server and start the synchrnonization against the new one discarding the old dataset.
The form redisSlaveOf(host="no",port="one") will stop replication, turning the server into a MASTER but will not discard the replication. So if the old master stop working it is possible to turn the slave into a master and set the application to use the new master in read/write. Later when the other Redis server will be fixed it can be configured in order to work as slave.