Originally from the User Slack
@TO: Hi all, need some thoughts or recommendations.
I want to run a three node of ScyllaDB cluster with each note in different data centres (geolocations). The data centres are about 30ms to 90ms apart.
Is this good, or will this set-up be potentially problematic?
@Felipe_Cardeneti_Mendes: Well, it is not common as you can imagine. I guess it is up to you to say whether this will be problematic or not, as you seem to already know beforehand the latency penalty for quorum and the risk in lower consistency levels.
@TO: Thanks @Felipe_Cardeneti_Mendes, I am entirely new to ScyllaDB.
In this case, how can the risks be managed in terms of quorum and consistency? Does Scylla support async replication?
Also, what would have been the best practise for multi datacentres (geolocations)?
@Felipe_Cardeneti_Mendes: ScyllaDB can be configured to fulfill the topology you want.
For example, you could have a multi-region cluster where each node is logically placed in a different region. This means that quorum queries will need to traverse regions and will impact latency. To avoid a latency impact, you could reduce the consistency level to ONE (or local_one), but the failure of a single node could cause data loss.
So you need to understand these trade-offs for this sort of topology. We do support async replication, and the best practice for multi-region clusters is to have at least 3 replicas in a primary region, potentially the same in other regions, but depending on your usage can be refined.
@TO: Thanks @Felipe_Cardeneti_Mendes for the insight.