Question-: You have decided to upgrade your Cassandra cluster from older version to newer version. And also, your older cluster has nodes and now in the new cluster you would be having nodes. Which all things you should do while migration preparation? A. Configure the same schema in the new 10 node cluster. B. Configure that client writes should go in both the cluster. C. Take the snapshot from the old cluster and copy the data files. D. Take the snapshot from the old cluster and copy the data using sstableloader. E. Switch to the new cluster
Answer: A,B,D,E
Explanation: There are few things you have to keep in mind when you migrate your Cassandra cluster. And should follow the below steps. 1. Create a new cluster with the 10 nodes. 2. Create the same keyspace in the new cluster as old one. 3. Access Mostly Uused Products by 50000+ Subscribers 4. Take the snapshot (point in time copy of the data) from the old cluster. 5. Copy snapshot data to new cluster. Now the point here is, if old cluster and new cluster are of the same size then you can directly copy the data files. This is only possible when a. In your old and new cluster, you are not using the vnodes. b. Both clusters are using the same version of the Cassandra (which is not the case, in given question) c. Number of nodes in old and new cluster is also same (this is not the case, in given question) 6. Hence, we have to use “sstableloader� to load the data in new cluster. 7. You can switch to new cluster at once or incremental migration to test the new cluster. 8. Once successful migration done and you see that new cluster works as expected, the decommission the old cluster.
Question-: You are having a node Cassandra cluster with the single token architecture, now you plan to add two more nodes to the Cassandra cluster. Which of the following is true in this case? A. Existing node should keep their existing token assignments. B. New nodes are assigned tokens that bisect the existing token range. C. You have to re-calculate the tokens for the entire cluster, and assign the new tokens to the existing nodes. D. It is fine, if you are having old data on the new nodes.
Answer: C
Explanation: As in the question it is clearly given that it is a single token architecture. So, it would be different approach to add new node to the existing cluster. There are basically two approach. 1. Add capacity by doubling the cluster size: This is one of the best approaches to increase the capacity of single token architecture cluster. Or you can even do the tripling, quadrupling the number of nodes. And this is a less complicated approach. With this approach existing nodes keep their existing token assignments, and the new nodes are assigned tokens that bisect the existing token range. 2. If you add non-uniform number of nodes: With this approach you have to recalculate the tokens for the entire cluster and assign the new tokens to the existing nodes. And make sure, your Cassandra new nodes are fresh and does not have old data in the directory saved_cache, commitlog, and hints.
Question-: You are adding new node to the existing Cassandra cluster which has single token architecture. You must keep the initial_token property as blank? A. True B. False
Answer: B
Explanation: If you keep the initial_token property empty then the database assigns the node a random token range and results in a badly unbalanced ring.