Standard XDCR topology?


#1

I know that XCDR has a lot of setup/tuning options, and I have read the documentation. But still have a couple questions…

  • If I configure all my clusters (say 5) to all talk to each other, will XDCR just “do the right thing” for efficient document sync? So if I update a doc on Cluster1, that change will flow to 2,3,4,5, and then will NOT flow from 2 to 3, because 3 already has the new data?

  • If I want all my clusters to be in sync, is the above the “standard” topology – just let all clusters talk to each other?

TIA,
Chuck


#2

@chuck.connell,
regarding-1 the answer is yes. with XDCR topology set up to take all the writes from 1 to 2,3,4 and 5, XDCR will replicate the correct changes and ignore replication if the data is up to date.

regarding-2 you can either form a ring (1-2-3-4-5-1 and so on) or you can do a star (1-2, 1-3, 1-4, 1-5, 2-1, 2-3, 2-4 and so on) Star can be chatty if you have a lot of updates but will have a lower latency replicating the changes to all clusters and ring can be efficient in replicating but will have a higher latency.
thanks
-cihan


#3

#1 – Thanks. That’s what I was hoping for.

#2 – Why not just set up XDCR from every cluster to every other cluster? Wouldn’t that result in minimal latency for a data change to reach all nodes, and also minimum chatter, since there would be no intermediate hops to move data?


#4

on #2 yes you are right. it just gets harder to add a remove new clusters. Star topology also would be a very tough one under 10-20 clusters. if you think 5 is your number, you can certainly do star
thanks
-cihan


#5

thanks. good point about how this gets harder with many nodes.