On 01/17/2011 09:28 PM, Jonathan Ellis wrote: > On Mon, Jan 17, 2011 at 2:10 PM, Samuel Benz <samuel.b...@switch.ch> wrote: >>>> Case1: >>>> If 'TEST' was previous stored on Node1, Node2, Node3 -> The update will >>>> succeed. >>>> >>>> Case2: >>>> If 'TEST' was previous stored on Node2, Node3, Node4 -> The update will >>>> not work. >>> >>> If you have RF=2 then it will be stored on 2 nodes, not 3. I think >>> this is the source of the confusion. >>> >> >> I checked the existence of the row on the different serverver with >> sstablekeys after flushing. So I saw three copies of every key in the >> cluster. > > If you want to be guaranteed to be able to read with two nodes down > and RF=3, you have to read at CL.ONE, since if the two nodes that are > down are replicas of the data you are reading (as in the 2nd case > here) Cassandra will be unable to achieve quorum (quorum of 3 is 2 > live nodes). >
Now it seems clear to me. Thanks! I was confused by the fact that: "live nodes" != "replica live nodes" Correct me if I'm wrong, but even in a cluster with 1000 nodes and RF=3, if I shut down the wrong two nodes, i have the same problem as in my mini cluster. -- Sam
