DataStax recommends saving your keyspaces before upgrading. Follow this procedure, which is recommended as a best practice.
To save old installation keyspaces:
Create a file in a directory for which you have permission that contains the SHOW KEYSPACES command. For example:
$ echo "SHOW KEYSPACES;" > /tmp/do_show.txt
Start CLI, using the -f option to execute the command in the saved file. Use the redirect function to save the output to another file in a directory for which you have permission. For example:
cd <old installation>/bin $ cassandra-cli -host localhost -port 9160 -f /tmp/do_show.txt > /tmp/my_saved_ks.txt
Check that the file, my_saved_ks.txt, contains the schema definition output of SHOW KEYSPACES.
Move the file containing the schema definition output to a safe location.
Upgrade to DataStax Enterprise 2.2.x. Do not run the nodetool scrub command. Follow one of these sets of instructions:
After the upgrade is complete, rerun the SHOW KEYSPACES command.
Check for any drastic changes in the keyspace list.
If any keyspaces disappeared during the upgrade:
Open the file containing the schema definitions that you saved in step 2 of the previous procedure.
Recreate keyspaces and table definitions:
Run the following command on the command line:
$ rm data/system/system_schema*
Using CQL or CLI, recreate the keyspaces and tables to replace the missing data: For example:
cd <old installation>/bin ./cqlsh --cql3 CREATE KEYSPACE <missing keyspace definition>; CREATE TABLE (<missing table definition>);