Different versions in a cassandra ring.

(2 posts) (2 voices)

• Started 5 months ago by sarch
• Latest reply from tycen-medio
• This topic is not a support question

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1. 

   sarch
   Member

   I'm new to cassandra. How will a cluster handle nodes that are running different versions of cassandra?

   ie, will a cluster with nodes that are running both 1.0.11 and 1.0.12 work happily together. I would *assume* so but can't find information on the subject.

   Similarly, what about 1.1.5 and 1.1.6.

   And what about running 1.0.12 and 1.1.5 together.

   Obviously this is not an idea situation but would like to know what happens in this situation.

   I'm running a cluster in AWS and need to migrate to a newer version of cassandra. For repeatability we just launch a different AMI with the new version of cassandra installed on it.

   So if I have 6 nodes with cassandra 1.0.12 on it, is it a sensible migration strategy to launch 6 new nodes with cassandra 1.1.6 on them, join the ring (so it's got a total of 12 nodes), then decommission the original 6? Or is it best to manually upgrade the original cluster to 1.1.6, then do the same migration pattern (add new nodes to get cluster of 12, then decommission the old nodes).

   Posted 5 months ago #
2. 

   tycen-medio
   Member

   I'm not an expert on this, but it worked fine for us short term to have different versions in the same ring. I just upgraded 10 nodes from 0.7.9 to 1.1.6 and had the ring online while I did it - upgrading one node at a time. You should also be able to do your plan of adding 6 new nodes with the new version then decommissioning the 6 old nodes.

   I think the bigger issue to look out for is any incompatibility issues between the versions your on and targeting. This page had a good list of changes between versions - read the "upgrading" section of each version between your current version and your target version to make sure there isn't anything that will cause trouble: https://github.com/apache/cassandra/blob/trunk/NEWS.txt

   Good luck.

   Posted 5 months ago #

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