Yes - using NetworkTopologyStrategy From: aaron morton [mailto:aa...@thelastpickle.com] Sent: Thursday, March 21, 2013 10:22 AM To: user@cassandra.apache.org Subject: Re: Question regarding multi datacenter and LOCAL_QUORUM
DEBUG [Thrift:1] 2013-03-19 00:00:53,313 ReadCallback.java (line 79) Blockfor is 2; setting up requests to /xx.yy.zz.146,/xx.yy.zz.143,/xx.yy.zz.145 DEBUG [Thrift:1] 2013-03-19 00:00:53,334 CassandraServer.java (line 306) get_slice DEBUG [Thrift:1] 2013-03-19 00:00:53,334 ReadCallback.java (line 79) Blockfor is 2; setting up requests to /xx.yy.zz.146,/xx.yy.zz.143 DEBUG [Thrift:1] 2013-03-19 00:00:53,366 CassandraServer.java (line 306) get_slice DEBUG [Thrift:1] 2013-03-19 00:00:53,367 ReadCallback.java (line 79) Blockfor is 2; setting up requests to /xx.yy.zz.146,/xx.yy.zz.143,/xx.yy.zz.145 This is Read Repair, as controlled by the read_repaur_chance and dclocal_read_repair_chance CF settings, in action. "Blockfor" is how many nodes the read operation is going to wait for. When the number of nodes in the request is more than blockfor it means Read Repair is active, we are reading from all UP nodes and will repair any detected differences in the background. Your read is waiting for 2 nodes to respond only (including the one we ask for the data.) The odd thing here is that there are only 3 replicas nodes. Are you using the Network Topology Strategy ? If so I would expect there to be 6 nodes in the the request with RR, 3 in each DC. Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 21/03/2013, at 12:38 PM, Tyler Hobbs <ty...@datastax.com<mailto:ty...@datastax.com>> wrote: On Wed, Mar 20, 2013 at 3:18 PM, Tycen Stafford <tstaff...@medio.com<mailto:tstaff...@medio.com>> wrote: I don't think that's correct for a mult-dc ring, but you'll want to hear a final answer from someone more authoritative. I could easily be wrong. Try using the built in token generating tool (token-generator) - I don't seem to have it on my hosts (1.1.6 also) so I can't confirm. I used the tokentoolv2.py tool (from here http://www.datastax.com/docs/1.0/initialize/token_generation) and got the following (which looks to me evenly spaced and not using offsets): tstafford@tycen-linux:Cassandra$ ./tokentoolv2.py 3 3 { "0": { "0": 0, "1": 56713727820156410577229101238628035242, "2": 113427455640312821154458202477256070485 }, "1": { "0": 28356863910078205288614550619314017621, "1": 85070591730234615865843651857942052863, "2": 141784319550391026443072753096570088106 } } For multi-DC clusters, the only requirement for a balanced cluster is that all tokens within a DC must be balanced; you can basically treat each DC as a separate ring (as long as your tokens don't line up exactly). So, either using an offset for the second DC or evenly spacing all nodes is acceptable. -- Tyler Hobbs DataStax<http://datastax.com/>
