2. It is confusing a little = bit. I would not use term "synchronous". Everything is asynchrono= us here. Coordinator writes data to all local nodes and waits for =A0respon= se from ANY two of them (in case of quorum). In your picture it looks like = the coordinator first makes decision what nodes should reply. It is not cor= rect.

On Tue,= Feb 11, 2014 at 9:36 AM, Mullen, Robert wrote:
So is that picture incorrec= t, or just incomplete missing the piece on how the nodes reply to the coord= inator node.

=
On Tue, Feb 11, 2014 at 9:38 AM, sankalp kohli <= span dir=3D"ltr"><kohlisankalp@gmail.com> wrote:
@Mullen,=A0
I think you= r diagram does not answer the question on responses.=A0
@Sameer
All nodes in DC2 will replay back to the co-ordinator in DC1. So if you hav= e replication of DC1:3,DC2:3. A co-ordinator node will get 6 responses back= if it is not in the replica set.=A0

On Tue, Feb 11, 2014 at 8:= 16 AM, Mullen, Robert wr= ote:
I had the same question a w= hile back and put together this picture to help me understand the flow of d= ata for multi region deployments. Hope that it helps.

On Mon, Feb 10, 2014 at 7:52 PM, Sameer Farooqui wrote:
Hi,=A0

I was hoping someone could clari= fy a point about multi-DC replication.

Let's s= ay I have 2 data centers configured with replication factor =3D 3 in each D= C.

My client app is sitting in DC 1 and is able to intelli= gently pick a coordinator that will also be a replica partner.
So the client app sends a write with consistency for DC1 =3D Q= and consistency for DC2 =3D Q to a coordinator node in DC1.

That coordinator in DC1 forwards the write to 2 other n= odes in DC1 and a coordinator in DC2.

Is it correc= t that all 3 nodes in DC2 will respond back to the original coordinator in = DC1? Or will the DC2 nodes respond back to the DC2 coordinator?

Let's say one of the replica nodes in DC2 is down. = Who will hold the hint for that node? The original coordinator in DC1 or th= e coordinator in DC2?=A0

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