Cassandra hot keyspace structure change
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by Pierre
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Published on 2010-04-01T23:42:53Z
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2010/04/01
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cassandra
Hello.
I'm currently running a 12-node Cassandra cluster storing 4TB of data, with a replication factor set to 3. For the needs of an application update, we need to change the configuration of our keyspace, and we'd like to avoid any downtime if possible.
I read on a mailing list that the best way to do it is to:
- Kill cassandra process on one server of the cluster
- Start it again, wait for the commit log to be written on the disk, and kill it again
- Make the modifications in the storage.xml file
- Rename or delete the files in the data directories according to the changes we made
- Start cassandra
- Goto 1 with next server on the list
My questions would be:
- Did I understand the process well?
- Is there any risk of data corruption?
- During the process, there will be servers with different versions of the storage.xml file in the same cluser, same keyspace. Is it a problem?
- Same question as above if we not only add, rename and remove ColumnFamilies, but if we change the CompareWith parameter / transform an existing column family into a super one. Or do we need to change the name?
Thank you for your answers. It's the first time I'll do this, and I'm a little bit scared.
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