Aaron, Can you point to a line in Cassandra sources where you believe it does not understand the "multi ring" approach? I'm not sure about Cassandra team but Hector team likes pull requests with patches. Anyways, I believe I should run a test to see if data is indeed replicated between datacenters.
And I voted on the issue. On Wed, Aug 17, 2011 at 2:20 AM, aaron morton <aa...@thelastpickle.com> wrote: > > The calculation for ownership does not understand the "multi ring" approach > to assigning tokens. I've > created https://issues.apache.org/jira/browse/CASSANDRA-3047 for you. > Otherwise your tokens look good to me. > Cheers > ----------------- > Aaron Morton > Freelance Cassandra Developer > @aaronmorton > http://www.thelastpickle.com > On 17/08/2011, at 9:19 AM, Oleg Tsvinev wrote: > > Hi all, > > I followed instructions here: > http://wiki.apache.org/cassandra/Operations#Token_selection > to create a Cassandra cluster spanning two datacenters. Now I see that > nodes belonging to DC2 datacenter own 0% of the ring. I would expect > them to own 50%. > > Does anyone have an idea what's going on here? > > root@casper02:~# nodetool -h 10.4.64.63 ring > Address DC Rack Status State Load > Owns Token > > 85070591730234615865843651857942052865 > 10.4.64.63 DC1 RAC1 Up Normal 36.19 MB > 50.00% 0 > 10.4.65.55 DC2 RAC1 Up Normal 36.21 MB > 0.00% 1 > 10.4.65.73 DC1 RAC1 Up Normal 530.12 KB > 50.00% 85070591730234615865843651857942052864 > 10.4.64.166 DC2 RAC1 Up Normal 525.68 KB > 0.00% 85070591730234615865843651857942052865 > > Thank you, > Oleg > > ------------- > > On Mon, Aug 15, 2011 at 1:39 PM, Oleg Tsvinev <oleg.tsvi...@gmail.com> wrote: > > Hi all, > > I have a question that documentation has not clear answer for. I have > > the following requirements: > > 1. Synchronously store data in datacenter DC1 on 2+ nodes > > 2. Asynchronously replicate the same data to DC2 and store it on 2+ > > nodes to act as a hot standby > > Now, I have configured keyspaces with o.a.c.l.NetworkTopologyStrategy > > with strategy_options=[{DC1:2, DC2:2}] and use LOCAL_QUORUM > > consistency level, following documentation here: > > http://www.datastax.com/docs/0.8/operations/datacenter > > Now, how do I assign initial tokens? If I have, say 6 nodes total, 3 > > in DC1 and 3 in DC2, and create a ring as if all 6 nodes share the > > total 2^128 space equally. > > Now say node N1:DC2 has key K and is in remote datacenter (for an app > > in DC1). Wouldn't Cassandra always forward K to the DC2 node N1 thus > > turning asynchronous writes into synchronous ones? Performance impact > > will be huge as the latency between DC1 and DC2 is significant. > > I hope there's an answer and I'm just missing something. My case falls > > under Disaster Recovery in > > http://www.datastax.com/docs/0.8/operations/datacenter but I don't see > > how Cassandra will support my use case. > > I appreciate any help on this. > > Thank you, > > Oleg > >
