I want to upgrade the Pulsar brokers in a pulsar cluster (from 2.6.3 to 2.10.1)
The question is could I just upgrade the brokers to 2.10.1 (and leave other components (Bookkeeper as well ZooKeeper) in 2.6.3)
(Asking this because according to this https://pulsar.apache.org/docs/administration-upgrade, I am not sure if I also need to upgrade BookKeeper or not)
Thank you !
2.6.3 contains a very old version of ZooKeeper (3.5.x) and from Pulsar 2.8.x onwards we require ZooKeeper 3.6.x because Pulsar uses the Persistent Recursive Watches feature.
I suggest to upgrade ZooKeeper and BookKeeper as well, at least to Pulsar 2.8.x.
As a general rule of thumb in Pulsar is that we support rolling upgrades from one major version to the next (so from 2.6 to 2.7...). Jumping from 2.6 to 2.10 is not supported officially, but it should work.
