Hi Just wanted to say that it worked. I also made sure to modify thrift rpc_port and storage port so that the two clusters don't interfere. Thanks for the suggestion
Thanks Rohit On Thu, Jul 12, 2012 at 10:01 AM, aaron morton <aa...@thelastpickle.com> wrote: > Since replication factor is 2 in first cluster, I > won't lose any data. > > Assuming you have been running repair or working at CL QUORUM (which is the > same as CL ALL for RF 2) > > Is it advisable and safe to go ahead? > > um, so the plan is to turn off 2 nodes in the first cluster, restask them > into the new cluster and then reverse the process ? > > If you simply turn two nodes off in the first cluster you will have reduce > the availability for a portion of the ring. 25% of the keys will now have at > best 1 node they can be stored on. If a node is having any sort of problems, > and it's is a replica for one of the down nodes, the cluster will appear > down for 12.5% of the keyspace. > > If you work at QUORUM you will not have enough nodes available to write / > read 25% of the keys. > > If you decomission the nodes, you will still have 2 replicas available for > each key range. This is the path I would recommend. > > If you _really_ need to do it what you suggest will probably work. Some > tips: > > * do safe shutdowns - nodetool disablegossip, disablethrift, drain > * don't forget to copy the yaml file. > * in the first cluster the other nodes will collect hints for the first hour > the nodes are down. You are not going to want these so disable HH. > * get the nodes back into the first cluster before gc_grace_seconds expires. > * bring them back and repair them. > * when you bring them back, reading at CL ONE will give inconsistent > results. Reading at QUOURM may result in a lot of repair activity. > > Hope that helps. > > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > > On 11/07/2012, at 6:35 AM, rohit bhatia wrote: > > Hi > > I want to take out 2 nodes from a 8 node cluster and use in another > cluster, but can't afford the overhead of streaming the data and > rebalance cluster. Since replication factor is 2 in first cluster, I > won't lose any data. > > I'm planning to save my commit_log and data directories and > bootstrapping the node in the second cluster. Afterwards I'll just > replace both the directories and join the node back to the original > cluster. This should work since cassandra saves all the cluster and > schema info in the system keyspace. > > Is it advisable and safe to go ahead? > > Thanks > Rohit > >
