Correct way to perform backup of Cassandra/Scylladb
For Scylla, please look at the following official documentation:


Backup your Data  


  
  Full Backup Snapshots are taken using nodetool snapshot.
  Enabling the incremental backup (disabled by default) will create a hard-link from each SSTable, right after it is flushed, to a backups directory.
  For a complete point in time backup you need: a snapshot plus incremental backups and commit logs since that time of the snapshot. Make sure to clean unnecessary incremental backup, Scylla will not do it for you.
  

Restore from a Backup and Incremental Backup


  Restoring a keyspace from backup requires all snapshot files of the tables, and incremental backup files taken after the snapshot - if available. Before restoring from backup, you should truncate the table data, making sure existing data will not override the restored one.  


See the linked documentation for detailed instructions.