Cedric, The problem you are seeing is that the list of vnodes does not spread perfectly between physical nodes. So with N=2 on only a 2 node cluster, you aren't given assurances that those two copies of data will end up on two vnodes owned by different physical nodes. So if you have data X on vnode 15 and 18 pretend, those two vnodes might both be owned by 192.168.0.21.
If you are running less (or equal) nodes than your N value, all bets are off when it comes to testing riak functionality. We suggest that you have a physical node count > N +1 to see Riak's true capabilities. If you just want to test functionality on a small scale, you can use the 'make devrel' setup to run 4 nodes on a single machine for testing [1]. Please do not test speed or throughput in that setup, but if you are trying to see how 2i works, that's a better option than two nodes with N=2. [1] http://wiki.basho.com/Building-a-Development-Environment.html Hope that helps, Jared On Mar 30, 2012, at 11:49 AM, Cedric Maion wrote: > Hey there, > > I'm playing with a two node riak 1.1.1 cluster, but can't figure how to > make riak happy with only one node (and the other one failed). > > My use case is the following: > - HTML pages gets stored in the riak cluster (it's used as a page cache) > - I'm using secondary indexes to tag those documents > - When I need to invalidate some HTML pages, I make a query on those > secondary indexes to retrieve the list of keys that needs to be deleted > (documents matching a specific tag value) > > The bucket is configured with > {"props":{"n_val":2,"allow_mult":false,"r":1,"w":1,"dw":0,"rw":1}}. > > Everything is working fine when both node are up and running. > However, if I turn one node off, secondary indexes queries returns > {error,{error,insufficient_vnodes_available}} errors. > > I can't find a way to have the cluster converge to a stable state on only one > node. > > > (192.168.0.21 is the node that has been turned off, by just stopping riak > with /etc/init.d/riak stop) > > > root@192.168.0.51:~# riak-admin member_status > Attempting to restart script through sudo -u riak > ================================= Membership================================== > Status Ring Pending Node > ------------------------------------------------------------------------------- > valid 50.0% -- 'riak@192.168.0.21' > valid 50.0% -- 'riak@192.168.0.51' > ------------------------------------------------------------------------------- > Valid:2 / Leaving:0 / Exiting:0 / Joining:0 / Down:0 > > > => 192.168.0.21 is not seen as being down, not sure if it's an issue or not > > > > root@192.168.0.51:~# riak-admin transfers > Attempting to restart script through sudo -u riak > Nodes ['riak@192.168.0.21'] are currently down. > 'riak@192.168.0.51' waiting to handoff 5 partitions > > > => by creating/reading many keys, I finally get "waiting to handoff 32 > partitions", which seems OK to me (ring size is 64, so each node should > normally own 32). > => however, secondary indexes queries always fails, until I turn the failed > node ON again. > > > I tried to force "riak-admin down riak@192.168.0.21" from the valid node, but > no luck either. > > Not being able to use secondary indexes while a node is down is a real > problem. > Is this expected behavior, or what am I missing? > > > Thanks in advance! > Kind regards, > > Cedric > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
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