hi Aaron: could you explain more about the issue about repair make space usage going crazy?
I am planning to upgrade my cluster from 0.7.4 to 0.8.6, which is because the repair never works on 0.7.4 for me. more specifically, CASSANDRA-2280<https://issues.apache.org/jira/browse/CASSANDRA-2280> and CASSANDRA-2156 <https://issues.apache.org/jira/browse/CASSANDRA-2156>. from your description, I really worried about 0.8.6 might make it worse... thanks! On Thu, Sep 22, 2011 at 7:25 AM, aaron morton <aa...@thelastpickle.com>wrote: > How much data is on the nodes in cluster 1 and how much disk space on > cluster 2 ? Be aware that Cassandra 0.8 has an issue where repair can go > crazy and use a lot of space. > > If you are not regularly running repair I would also repair before the > move. > > The repair after the copy is a good idea but should technically not be > necessary. If you can practice the move watch the repair to see if much is > transferred (check the logs). There is always a small transfer, but if you > see data been transferred for several minutes I would investigate. > > When you start a repair it will repair will the other nodes it replicates > data with. So you only need to run it every RF nodes. Start it one one, > watch the logs to see who it talks to and then start it on the first node it > does not talk to. And so on. > > Add a snapshot before the clean (repair will also snapshot before it runs) > > Scrub is not needed unless you are migrating or you have file errors. > > If your cluster is online, consider running the clean every RFth node > rather than all at once (e.g. 1,4, 7, 10 then 2,5,8,11). It will have less > impact on clients. > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Developer > @aaronmorton > http://www.thelastpickle.com > > On 22/09/2011, at 10:27 AM, Philippe wrote: > > Hello, > We're currently running on a 3-node RF=3 cluster. Now that we have a better > grip on things, we want to replace it with a 12-node RF=3 cluster of > "smaller" servers. So I wonder what the best way to move the data to the new > cluster would be. I can afford to stop writing to the current cluster for > whatever time is necessary. Has anyone written up something on this subject > ? > > My plan is the following (nodes in cluster 1 are node1.1->1.3, nodes in > cluster 2 are node2.1->2.12) > > - stop writing to current cluster & drain it > - get a snapshot on each node > - Since it's RF=3, each node should have all the data, so assuming I > set the tokens correctly I would move the snapshot from node1.1 to node2.1, > 2.2, 2.3 and 2.4 then node1.2->node2.5,2.6,2.,2.8, etc. This is because the > range for node1.1 is now spread across 2.1->2.4 > - Run repair & clean & scrub on each node (more or less in //) > > What do you think ? > Thanks > > >
