CODEWITHSUNDEEP
hadoopcassandradatastax-enterprise
Tripti
Tripti

Reputation: 85

How to check vnode disabled on a hadoop node

Linking back to this question: Why not enable virtual node in an Hadoop node?

I'm running a mixed 3 node cluster with 2 cassandra and 1 analytics nodes and disabled the virtual nodes by generating 3 tokens with the utility given by DataStax enterprise. But when I run 'nodetool status' command, I still see 256 tokens with each node and when a mapreduce job is created, it creates 257 mappers and takes a very long time to execute a query with small data. So my specific questions are:

  1. Is virtual node setting still not disabled? How can I verify if its disabled?

  2. If its disabled then why 257 mappers are still created for each job? Is there a different configuration for that?

Thanks much for any help!!

Upvotes: 0

Views: 981

Answers (1)

RussS
RussS

Reputation: 16576

1) It's not disabled. You can tell because it still says 256 tokens in nodetool status.

To disable vnodes you need to make sure that you change the num_tokens variable in the cassandra.yamnl

# If you already have a cluster with 1 token per node, and wish to migrate to 
# multiple tokens per node, see http://wiki.apache.org/cassandra/Operations
# num_tokens: 256  << Make sure this line is commented out

# initial_token allows you to specify tokens manually.  While you can use it with
# vnodes (num_tokens > 1, above) -- in which case you should provide a 
# comma-separated list -- it's primarily used when adding nodes to legacy clusters 
# that do not have vnodes enabled.
initial_token:  << Your generated token goes here

Upvotes: 3

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