Here is my understanding. Corrections welcome. You're missing that Riak is happy to be "eventually consistent". Drop out 2 of your nodes, and it rebalances who is responsible for what, then under the hood migrates and replicates its data more leisurely.
Data is still being written to 4 different hash buckets, but those buckets are now distributed across 2 machines. When the data is done migrating, you should not have lost any data. But it might be temporarily available. On Fri, May 13, 2011 at 8:13 AM, Peter Fales <peter.fa...@alcatel-lucent.com> wrote: > > I'm a Riak newbie, trying to get some familiarity with the system by > runing some tests on Amazon EC2. I'm seeing some behavior that I don't > understand... > > I've set up a test where I create a 4-node cluster using 4 EC2 machines. > I've created a bucket with n_val=4, r=quorum, and w=quorum. For > n_val=4, the quorum should be 3, so I thought I would have to have at > least 3 nodes in service for my read and write operations to succeed. > During my test, I start sending read/write requests to two of the nodes > (and I see the CPU load go up on all four nodes, so I know they are > talking to each other). Then I reboot the other two nodes. At that > point, I was expecting the reads and writes to start failing, but in > fact I usually don't see any problems. (sometimes the query that is > in progress at the time may fail or timeout, but if I establish a new > connection to the server, and start sending read/write requests again, > those requests will go through, even with only two of the 4 nodes in service) > > I suspect I'm just missing something obvious, but I don't understand how > I can run with just two nodes. What am I missing? > > -- > Peter Fales > Alcatel-Lucent > Member of Technical Staff > 1960 Lucent Lane > Room: 9H-505 > Naperville, IL 60566-7033 > Email: peter.fa...@alcatel-lucent.com > Phone: 630 979 8031 > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com > _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
