Restore data in Cassandra 3.9. from snapshot taken in Cassandra 2.1.15

Question

Did someone know, how to restore data in Cassandra 3.9. from snapshot taken in Cassandra 2.1.15 (before I upgraded Cassandra)?

Just copying snapshot files into proper data directory and executing "nodetool refresh" didn't work.

Answer 1

Cassandra use sstables to save data into files. These sstables have a version.

Cassandra 2.1.15 supports sstable versions : ja (2.0.0), jb (2.0.1), ka (2.1.0):

Cassandra 3.9 supports sstable versions : jb (2.0.1), ka (2.1.0), la (2.2.0), lb (2.2.7), ma (3.0.0), mb (3.0.7, 3.7), mc (3.0.8, 3.9)

When upgrading cassandra , you must use 'nodetool upgradesstable' to upgrade sstable format version to latest available before and after upgrading cassandra.

I think your sstables are in version ja (2.0.0) that is not supported by cassandra 3.9.

Answer 2

Try to run nodetool upgradesstables.

Otherwise you can downgrade your 3.9 cluster to the version that supports your version sstbales version and upgrade it back afterwards.

And most secure option - create a side 2.1 cluster with 2.1 snapshots, and upgrade it until you get a needed version of sstables, take snapshot, restore to your 3.9 cluster.