I had actually meant to (and thought I did) type "greater than zero and less than *or equal* to number of nodes".
That being said, you usually do want it less than the number of nodes in the cluster because otherwise your cluster essentially has the same performance as a single node. In general (fuzzy) performance is num_nodes / RF. If you have 9 nodes and RF=3 you have performance roughly along the lines of having 3 boxen. If you have N nodes and RF=N, you have roughly the same performance as... one machine. What Arron says about RF and Consistency Level (CL) is also correct. RF=2 implies CL.Q requires both nodes meaning you can't lose a single node and still read/write at CL.Q Just to be pedantic though, you have have a cluster of N nodes (for large N) and read/write at CL.Q even after losing some nodes. For example, if you have 10 nodes and RF=10 you only need 6 nodes up to read/write at CL.Q On Mon, Feb 14, 2011 at 6:58 PM, Aaron Morton <aa...@thelastpickle.com>wrote: > He probably meant in production. When playing around, and if you only have > 2 nodes, you can set it to 2. > > From memory RF of 2 means the Quorum is also 2, so you cannot afford to > lose one. Thats fine for playing. > > Aaron > > > On 15 Feb, 2011,at 01:51 PM, mcasandra <mohitanch...@gmail.com> wrote: > > > > mcasandra wrote: > > > > In earlier post same thread you mentioned that replication factor should > > be set to less than N. > > > > Currently I am testing on 2 node cluster and I was able to set > > replication_factor to 2 (=N) and also when I did cfstats (I don't quite > > understand cfstats in detail) and see some activity on both nodes now > > > > [default@twissandra] update keyspace twissandra with > replication_factor=2; > > 3ed6b708-389b-11e0-993f-b7fa7ed61af9 > > [default@twissandra] set users['b']['add']='111'; > > Value inserted. > > > > On the other node when I ran nodetool with -h as localhost, I see: > > > > > > Column Family: users > > SSTable count: 0 > > Space used (live): 0 > > Space used (total): 0 > > Memtable Columns Count: 2 > > Memtable Data Size: 52 > > Memtable Switch Count: 0 > > Read Count: 3 > > Read Latency: NaN ms. > > Write Count: 2 > > Write Latency: NaN ms. > > Pending Tasks: 0 > > Key cache capacity: 200000 > > Key cache size: 0 > > Key cache hit rate: NaN > > Row cache: disabled > > Compacted row minimum size: 0 > > Compacted row maximum size: 0 > > Compacted row mean size: 0 > > > > > Sorry I meant to say someone (Matthew Dennis) on the thread mentioned that > replication factor should be less than no. of nodes. > -- > View this message in context: > http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Internal-error-processing-insert-tp6025740p6025882.html > Sent from the cassandra-u...@incubator.apache.org mailing list archive at > Nabble.com. > >
