Since DM 10.2.0 CU9, the default Replication strategy will be NetworkTopologyStrategy (for clusters of more than 1 node).
In the docs, it says that the replication factor will be set to 3 (in a cluster with at least 4 nodes).
What will the default settings be in a 3-datacenter Cassandra cluster with each 6 nodes?
Will there be 3 replicas in each datacenter (so 9 in total)?
Is there a way to configure this default in DataMiner? If for example we would like 3 replicas in 1 datacenter, but only 1 in the other 2 datacenters to save some resources.
Hi Matthijs,
AFAIK, there is no option to tweak the defaults ATM, but once the tables are created you can tweak the RF on your datacenters in Cassandra. You can also make use of the Apache Cassandra Cluster Monitor connector to see if there would be any tables/keyspaces with incorrect settings and alarm on it.
Thanks for the confirmation.
After migration we can change the settings, but we then probably have to do a repair on the changed tables.
It’s a bit more annoying for new tables after an upgrade or a new element with a logger table for example, but we will keep an eye on it manually for now.
The default will be 3 on the condition that each datacenter has 3 or more nodes.
So for the situation where there are 3 DCs with 6 nodes each, there will be 9 replicas. 3 per DC. If a DC has less than 3 nodes then we’ll default to a replication factor of 1 there.
There’s no possibility to tweak these settings through DataMiner, but once the tables are created we no longer change this setting at runtime.
So as Michiel mentioned, you can then further tweak & refine the replication factor settings per table.