Atin Sood created CASSANDRA-12510:
-------------------------------------
Summary: Decommission process should raise an error flag when
nodes in a DC don't have any nodes to stream data to
Key: CASSANDRA-12510
URL: https://issues.apache.org/jira/browse/CASSANDRA-12510
Project: Cassandra
Issue Type: Bug
Components: Streaming and Messaging
Environment: C* version 3.3
Reporter: Atin Sood
Priority: Minor
Steps to replicate :
- Create a 3 node cluster in DC1 and create a keyspace test_keyspace with table
test_table with replication strategy NetworkTopologyStrategy , DC1=3 . Populate
some data into this table.
- Add 5 more nodes to this cluster, but in DC2. Also do not alter the keyspace
to add the new DC2 to replication (this is intentional and the reason why the
bug shows up). So the desc keyspace should still list NetworkTopologyStrategy
with DC1=3 as RF
- As expected, this will now be a 8 node cluster with 3 nodes in DC1 and 5 in
DC2
- Now start decommissioning the nodes in DC1. Note that the decommission runs
fine on all the 3 nodes, but since the new nodes are in DC2 and the RF for
keyspace is restricted to DC1, the new 5 nodes won't get any data.
- You will now end with the 5 node cluster which has no data from the
decommissioned 3 nodes and hence ending up in data loss
I do understand that this problem could have been avoided if we perform an
alter stmt and add DC2 replication before adding the 5 nodes. But the fact that
decommission ran fine on the 3 nodes on DC1 without complaining that there were
no nodes to stream its data seems a little discomforting.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
