My understanding is that the replication factor is for the entire ring. Even if you have 2 DCs the nodes are part of the same ring. What you get additionally from NTS is that you can specify how many replicas to place in each DC.
So RF = 1 and DC1:1, DC2:1 looks incorrect to me. What is possible with NTS is following: RF=3, DC1=1, DC2=2 Would wait for others comments to see if my understand is correct. -Naren On Wed, May 11, 2011 at 5:41 PM, Anurag Gujral <anurag.guj...@gmail.com>wrote: > Thanks Sameer for your answer. > I am using two DCs DC1 , DC2 with both having one node each, my > straegy_options values are DC1:1,DC2:1 I am not sure what my RF should be , > should it be 1 or 2? > Please Advise > Thanks > Anurag > > > On Wed, May 11, 2011 at 5:27 PM, Sameer Farooqui > <cassandral...@gmail.com>wrote: > >> Anurag, >> >> The Cassandra ring spans datacenters, so you can't use token 0 on both >> nodes. Cassandra’s ring is from 0 to 2**127 in size. >> >> Try assigning one node the token of 0 and the second node 8.50705917 × >> 10^37 (input this as a single long number). >> >> To add a new keyspace in 0.8, run this from the CLI: >> create keyspace KEYSPACENAME with placement_strategy = >> org.apache.Cassandra.locator.NetworkTopologyStrategy' and strategy_options = >> [{replication_factor:2}]; >> >> If using 0.7, run "help create keyspace;" from the CLI and it'll show you >> the correct syntax. >> >> >> More info on tokens: >> >> http://journal.paul.querna.org/articles/2010/09/24/cassandra-token-selection/ >> <http://journal.paul.querna.org/articles/2010/09/24/cassandra-token-selection/> >> http://wiki.apache.org/cassandra/Operations#Token_selection >> >> >> On Wed, May 11, 2011 at 4:58 PM, Anurag Gujral >> <anurag.guj...@gmail.com>wrote: >> >>> Hi All, >>> I am testing network topology strategy in cassandra I am >>> using two nodes , one node each in different data center. >>> Since the nodes are in different dc I assigned token 0 to both the nodes. >>> I added both the nodes as seeds in the cassandra.yaml and I am using >>> properyfilesnitch as endpoint snitch where I have specified the colo >>> details. >>> >>> I started first node then I when I restarted second node I got an error >>> that token "0" is already being used.Why am I getting this error. >>> >>> Second Question: I already have cassandra running in two different data >>> centers I want to add a new keyspace which uses networkTopology strategy >>> in the light of above errors how can I accomplish this. >>> >>> >>> Thanks >>> Anurag >>> >> >> > -- Narendra Sharma Solution Architect *http://www.persistentsys.com* *http://narendrasharma.blogspot.com/*