1 - no, unless broker4 is not the preferred leader. (The preferred
leader is the first broker in the assigned replica list). If a
non-preferred replica is the current leader you can run the
PreferredReplicaLeaderElection admin command to move the leader.
2 - The actual leader movement (on leader failover) is fairly low -
probably of the order of tens of ms. However, clients (producers,
consumers) may take longer to detect that (it needs to get back an
error response, handle an exception, issue a metadata request, get the
response to find the new leader, and all that can add up but it should
not be terribly high - I'm guessing on the order of a few hundred ms
to a second or so).
3 - That should work, although the admin command for adding more
partitions to a topic is currently being developed.
On Mon, Jul 8, 2013 at 11:02 PM, Calvin Lei <[EMAIL PROTECTED]> wrote:

 
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