I would replicate your different keyspaces to different DCs and scale those appropriately So, for example, HighLoad KS replicates to really-huge-dc, which would have, 10 nodes, LowerLoad KS replicates to smaller-dc with 5 nodes. The idea is , you do not mix your different keyspaces in the same datacenter ( this is possible with NetworkTopology ) or for redundancy/HA purposes you place a single replica in the other keyspace's DC but you direct your applications to the "primary" DC of the keyspace, with LOCAL_QUORUM or ONE reads.
Regards, Andras From: Matthias Zeilinger <matthias.zeilin...@bwinparty.com<mailto:matthias.zeilin...@bwinparty.com>> Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>> Date: Friday 12 April 2013 07:57 To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" <user@cassandra.apache.org<mailto:user@cassandra.apache.org>> Subject: RE: multiple Datacenter values in PropertyFileSnitch I´m using for each application it´s own keyspace. What I want is to split up for different load patterns. So that 2 apps with same and very high load pattern are not clashing. For other load patterns I want to use another splitting. Is there any best practice or should I scale out, so that the complete load can be distributed to on all nodes? Br, Matthias Zeilinger Production Operation – Shared Services P: +43 (0) 50 858-31185 M: +43 (0) 664 85-34459 E: matthias.zeilin...@bwinparty.com<mailto:matthias.zeilin...@bwinparty.com> bwin.party services (Austria) GmbH Marxergasse 1B A-1030 Vienna www.bwinparty.com From: aaron morton [mailto:aa...@thelastpickle.com] Sent: Donnerstag, 11. April 2013 20:48 To: user@cassandra.apache.org<mailto:user@cassandra.apache.org> Subject: Re: multiple Datacenter values in PropertyFileSnitch A node can only exist in one DC and one rack. Use different keyspaces as suggested. Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 12/04/2013, at 1:47 AM, Jabbar Azam <aja...@gmail.com<mailto:aja...@gmail.com>> wrote: Hello, I'm not an expert but I don't think you can do what you want. The way to separate data for applications on the same cluster is to use different tables for different applications or use multiple keyspaces, a keyspace per application. The replication factor you specify for each keyspace specifies how many copies of the data are stored in each datacenter. You can't specify that data for a particular application is stored on a specific node, unless that node is in its own cluster. I think of a cassandra cluster as a shared resource where all the applications have access to all the nodes in the cluster. Thanks Jabbar Azam On 11 April 2013 14:13, Matthias Zeilinger <matthias.zeilin...@bwinparty.com<mailto:matthias.zeilin...@bwinparty.com>> wrote: Hi, I would like to create big cluster for many applications. Within this cluster I would like to separate the data for each application, which can be easily done via different virtual datacenters and the correct replication strategy. What I would like to know, if I can specify for 1 node multiple values in the PropertyFileSnitch configuration, so that I can use 1 node for more applications? For example: 6 nodes: 3 for App A 3 for App B 4 for App C I want to have such a configuration: Node 1 – DC-A& DC-C Node 2 – DC-B & DC-C Node 3 – DC-A & DC-C Node 4 – DC-B & DC-C Node 5 – DC-A Node 6 – DC-B Is this possible or does anyone have another solution for this? Thx & br matthias
