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cassandradatastaxdatastax-enterprise

DSE 5 and DSE 4.8.9 in Same Cluster

Is it at all possible to have two different DSE versions in the same cluster? In my case, I have a a cluster of two DSE 5 nodes and another one of two DSE 4.8.9 nodes. Can I connect them such that data is replicated from DSE 4.8.9 to DSE 5 in real time?

Solution

  • No. If you were to try this, you'd be in an "Upgrade State." And clusters in an upgrade state are bound by these restrictions:

    • Do not enable new features.
    • Do not run nodetool repair.
    • Do not issue these types of CQL queries during a rolling restart: DDL and TRUNCATE.
    • During upgrades, the nodes on different versions might show a schema disagreement.
    • Failure to upgrade SSTables when required results in a significant performance impact and increased disk usage.
    • Upgrading is not complete until the SSTables are upgraded.

    Trying something like this would be further exacerbated by the fact that 4.8.9 is based on Cassandra 2.1 and 5.0 is based on Cassandra 3.0. There were some significant changes between the two, so you would undoubtedly run into problems.

    The best way to go about this would be to upgrade your 4.8.9 nodes to 5.0 first, and then add your new 5.0 cluster nodes afterward.