Re: Clarification on how multi-DC replication works

2014-02-11 Thread sankalp kohli
@Mullen, I think your diagram does not answer the question on responses. @Sameer All nodes in DC2 will replay back to the co-ordinator in DC1. So if you have replication of DC1:3,DC2:3. A co-ordinator node will get 6 responses back if it is not in the replica set. Hope that answers your question.

Re: Clarification on how multi-DC replication works

2014-02-11 Thread Mullen, Robert
So is that picture incorrect, or just incomplete missing the piece on how the nodes reply to the coordinator node. On Tue, Feb 11, 2014 at 9:38 AM, sankalp kohli kohlisank...@gmail.comwrote: @Mullen, I think your diagram does not answer the question on responses. @Sameer All nodes in DC2

Re: Clarification on how multi-DC replication works

2014-02-11 Thread Andrey Ilinykh
1. reply part is missing. 2. It is confusing a little bit. I would not use term synchronous. Everything is asynchronous here. Coordinator writes data to all local nodes and waits for response from ANY two of them (in case of quorum). In your picture it looks like the coordinator first makes

Re: Clarification on how multi-DC replication works

2014-02-11 Thread Mullen, Robert
Thanks for the feedback. The picture shows a sample request, which is why the coordinator points to two specific nodes. What I was trying to convey that the coordinator node would ensure that 2 of the 3 nodes were written to before reporting success to the client. I found the article here, it

Re: Clarification on how multi-DC replication works

2014-02-11 Thread Andrey Ilinykh
On Tue, Feb 11, 2014 at 10:14 AM, Mullen, Robert robert.mul...@pearson.comwrote: Thanks for the feedback. The picture shows a sample request, which is why the coordinator points to two specific nodes. What I was trying to convey that the coordinator node would ensure that 2 of the 3 nodes

Re: Clarification on how multi-DC replication works

2014-02-11 Thread Mullen, Robert
The picture shows a sample request, which is why the coordinator points to two specific nodes. What I was trying to convey that the coordinator node would ensure that 2 of the 3 nodes were written to before reporting success to the client. This is my point. ANY 2 of 3. Your picture shows

Re: Clarification on how multi-DC replication works

2014-02-11 Thread graham sanderson
slightly off topic, but does anyone know off the top of their head what happens if data is being written at LOCAL_QUORUM to a multi data center setup faster than the inter data center link can handle… something has to block, throw an exception, die, or have unbounded growth (memory, threads, on

Clarification on how multi-DC replication works

2014-02-10 Thread Sameer Farooqui
Hi, I was hoping someone could clarify a point about multi-DC replication. Let's say I have 2 data centers configured with replication factor = 3 in each DC. My client app is sitting in DC 1 and is able to intelligently pick a coordinator that will also be a replica partner. So the client app