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 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.
Your list looks like the one in http://wiki.apache.org/cassandra/FAQ#modify_cf_config. So it should be accurate…