Regarding upgrade from 2.0.3 to 2.0.7

Question

I am currently planning for an upgrade to 2.0.7 cassandra version . My base version is 2.0.3. I have not done an upgrade so far and hence want to be absolutely sure about what am doing . Can someone explain what needs to be done apart front this.

1. Do a nodetool drain to stop all writes to the particular node.
2. Stop the cassandra node(I have a 8 node , 2 data center network topology. I am bringing down one node in DC1)
3. Change the cassandra.yaml accordingly in the new binary tarball.
4. Make the required changes for the new node(using gossiping property file snitch. So , making changes for that)
5. Start off the new cassandra binary(2.0.7)

Question striking me the most

1. Do I have to copy the data from 2.0.3 to 2.0.7? 2.Even if it's a rolling upgrade , I think the following steps will do( Except moving from one version to another ) . My assumption is right?
2. Am going to do this operation on a running application. Am planning to have the application running while doing this as I have enough replicas in local quorum to satisfy reads and writes. Does this idea have any disadvantages ? I loved cassandra for this kind of operation but would like to know of there are any potential problems ?
3. I will be having the existing 2.0.3 in my running machine while doing this. If there is a problem in 2.0.7 , I shall start off 2.0.3 version again right? Just wanted to know whether there will be any data conflicts with other nodes in the cluster? Or having a snapshot to recover the data is the best option? 5.Apart from this, any other thing I have bear in mind?

Answer 1

Do I have to copy the data from 2.0.3 to 2.0.7? 2.Even if it's a rolling upgrade , I think the following steps will do( Except moving from one version to another ) . My assumption is right?

If you just upgrade the binaries, you can leave all of the data in place and it will use it automatically.

Am going to do this operation on a running application. Am planning to have the application running while doing this as I have enough replicas in local quorum to satisfy reads and writes. Does this idea have any disadvantages ? I loved cassandra for this kind of operation but would like to know of there are any potential problems ?

Normal read and write operations are fine. While you are temporarily running a mixed-version cluster, it's best to avoid doing anything that involves streaming (repairs) or topology changes (bootstrapping or decommissioning nodes). They might work, but they're not officially supported and you're more likely to have problems.

I will be having the existing 2.0.3 in my running machine while doing this. If there is a problem in 2.0.7 , I shall start off 2.0.3 version again right? Just wanted to know whether there will be any data conflicts with other nodes in the cluster? Or having a snapshot to recover the data is the best option?

You want to have a snapshot to recover from. Newer versions of Cassandra may use new SSTable or commitlog formats which the older version will not be able to read.