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From Robert Wille <rwi...@fold3.com>
Subject Upgrade instructions don't make sense
Date Mon, 23 Nov 2015 22:55:55 GMT
I’m wanting to upgrade from 2.0 to 2.1. The upgrade instructions at http://docs.datastax.com/en/upgrade/doc/upgrade/cassandra/upgradeCassandraDetails.html
has the following, which leaves me with more questions than it answers:

If your cluster does not use vnodes, disable vnodes in each new cassandra.yaml before doing
the rolling restart.
In Cassandra 2.0.x, virtual nodes (vnodes) are enabled by default. Disable vnodes in the 2.0.x
version before upgrading.

  1.  In the cassandra.yaml<http://docs.datastax.com/en/upgrade/doc/upgrade/cassandra/upgradeCassandraDetails.html#upgradeCassandraDetails__cassandrayaml_unique_7>
file, set num_tokens to 1.
  2.  Uncomment the initial_token property and set it to 1 or to the value of a generated
token<http://docs.datastax.com/en/cassandra/2.1/cassandra/configuration/configGenTokens_c.html>
for a multi-node cluster.

It seems strange that vnodes has to be disabled to upgrade, but whatever. If I use an initial
token generator to set the initial_token property of each node, then I assume that my token
ranges are all going to change, and that there’s going to be a whole bunch of streaming
as the data is shuffled around. The docs don’t mention that. Should I wait until the streaming
is done before proceeding with the upgrade?

The docs don’t talk about vnodes and initial_tokens post-upgrade. Can I turn vnodes back
on? Am I forever after stuck with having to have manually generated initial tokens (and needing
to have a unique cassandra.yaml for every node)? Can I just set num_tokens = 256 and comment
out initial_token and do a rolling restart?

Thanks in advance

Robert


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