Cassandra备份还原

Question

I am restoring Cassandra[3.10] backup using the snapshots. I have taken the backup of all the keyspaces, but there are additional keyspaces in Cassandra like system_distributed,system_auth,system_schema, system. My question is while restoring do we also need this to be restored?

Below is the link that I followed http://docs.datastax.com/en/cassandra/2.1/cassandra/operations/ops_backup_snapshot_restore_t.html#ops_backup_snapshot_restore_t

Answer 1

You should NOT restore system keyspaces, except for the system_auth keyspace (you need this for the logins to work). You can run into issues by doing so. I supported recently a production system which had that type of problems because they backed up and restored the system keyspaces. I can't remember what the issue was, but I remember it had to do with the restore of these tables that kept values which should not be "recycled."

Cassandra will create the system keyspaces on startup if they don't exist already.

Equally important is to backup a schema version. You will need the schema corresponding to the backup that you are restoring. Otherwise, if your schema changed since your last backup, the restore will not go well.

Answer 2

You can choose not to restore system keyspaces. Cassandra stores its state in System keyspace tables, basically it contain details about your database objects and cluster configuration. Refer to this link system keyspace information . Those information will be created when you would do a backup. For example:

select * from system_schema.tables;

You would see a bunch of information like gc_grace_seconds , memtable_flush_period_in_ms etc.