Is there a limit on replication factor? Can a large replication factor cause issues?


#1

Hi

We have a certain situation in which all of our data is stored on all the nodes. This is mainly to handle hotspotting. We are keeping replication factor same as the number of nodes for achieving this.

Our cluster size will be somewhere around 15-20 nodes. And our operations will be mostly reads (99:1 RW ratio)

I just wanted to check if it’s advisable to have such a large replication factor. Can it cause some problems ?We are majorly concerned about stability problems like crash, cluster-integrity etc.

Kindly throw some light on this. Many Thanks.


#2

We have a production user doing full replication in a 5 node cluster and have been running for ~ 1 year this way. Their dataset being replicated this way is only updated once a day in their case. I’m not aware of any stability issues with large replication factors, but it is a far less deployed configuration.


#3

Thanks @kporter

What’s the expected behavior when I bring down few nodes in such a setup? Say 15 nodes with 15 replication factor and then 2 nodes are brought down. Should it trigger any migration ? I am not seeing that actually in my setup when I brought down 2 nodes. And not able to understand if that’s correct behavior.


#4

Interesting, I hadn’t really considered this before but yes, I wouldn’t expect migrations when you remove a node in a fully replicated cluster. When you add these nodes back there will be migrations; the amount of migration could be improved by wiping these nodes before they return.