On 10/3/2019 2:45 AM, Norbert Kalmar wrote:
As for running a mixed version of 3.5 and 3.4 quorum - I'm afraid it will
not work. From 3.5 we have a check on PROTOCOL_VERSION. 3.4 did not have
this protocol version, so when the nodes try to communicate it will throw
an exception. Plus, it is not a goal to keep quorum protocol backward
compatible, so chances are even without the check it would not work.
This document suggests that a mixed environment of 3.4 and 3.5 will work:
https://cwiki.apache.org/confluence/display/ZOOKEEPER/ReleaseManagement
But you seem to be saying that it won't.
As a committer on the Lucene/Solr project (which uses ZK) I am wondering
what we can tell our users about upgrading ZK. I was under the
impression from the wiki page I linked that they could do a rolling
upgrade with zero downtime, where they do one ZK server at a time. Are
you saying that this is not possible?
The Upgrade FAQ that you linked doesn't say anything about 3.4 and 3.5
not working together. The only big gotcha I see there is
ZOOKEEPER-3056, which has a workaround.
(I think of 4lw whitelisting as just a config problem with a new
default, not a true upgrade issue)
Thanks,
Shawn
