Hi all,
In a system where single external cassandra and elastic nodes are going to be implemented, does the Cassandra cluster migrator tool help even we will not use DB clusters?
During the migration, will the data be moved or copied to the DB nodes?
Any risk of loosing data?
Are we expecting a high memory or CPU usage in the Dataminer server during the migration process?
Thanks.
The Cassandra migration cluster tool as documented here will migrate your data from the local cassandra db (and eventual elastic db) to a new location specified while using the tool.
In reality it will set up a new connection to the new db locations and write new data to both locations (for Cassandra). Once you actually start the migration it will copy the data from the old Cassandra to the new Cassandra. If you already had an elastic configured before the migration it will reuse this db. It WILL delete any alarm data there if any existed, but this data was redundand because it also exists in Cassandra, so any data deleted there will be copied again from Cassandra.
Only during the finalization is the DMS restarted and will only the new connection be used, so if you need to abort the migration you will still have the old connection and data from before. I would advise to restart your DMS after aborting the migration though.
The migration is throttled normally, but if you would still encounter memory spikes you can opt to migrate specific storagetypes one by one to spread the load.
You can use this migration tool even if your target cassandra only has a single node. It is still useful as the new DB structure will be more efficiënt for DataMiner version 10.2.0.0 and onward.