If I don't do any map/reduce jobs, still JobTracker/TaskTrackers need to be running for some HBase internal dependency?
No you don't need both for running solely HBase.
Just a tip: there are always scripts that just start the HDFS, bin/start-dfs.sh for example.
As mentioned above we don't need Job/Tasktracker if we are dealing with just Hbase. You can use bin/start-dfs.sh to start Name/Dtanodes..Moreover bin/start-all.sh has been deprecated now..So you should prefer using bin/start-dfs.sh to start Name/Datanodes and bin/start-mapred.sh to start Job/Tasktracker..I would suggest using Hbase in pseudo-distributed mode for learning and testing purpose, as in standalone Hbase doesn't use HDFS..You should be a bit careful while configuring though..
Basic case: You don't need JobTracker and TaskTrackers when using only HDFS+HBase (in smaller, testing environment you don't need event HDFS)
When you would like to run MapReduce jobs using data stored in HBase, you'll obviously need both JobTracker and TaskTrackers.
