The steps are the same for RUS -> RAS no matter what version of Cassandra you are on, but 0.7 introduced NTS which is designed to make adding datacenters easier.
On Thu, Jul 28, 2011 at 6:57 AM, Ashley Martens <amart...@ngmoco.com> wrote: > Thank you. For 0.7 are the steps similar? > > > > On Jul 27, 2011, at 19:56, Jonathan Ellis <jbel...@gmail.com> wrote: > >> As you know, with 0.6 adding a datacenter is not as easy as 0.7 with >> NetworkTopologyStrategy. With 0.6 there is a right way that will work >> with some manual effort, and a wrong way that can cause you major pain >> and grief. >> >> The right way: >> - Switch to a DC-aware snitch but leave your cluster on RUS to start with. >> - Bootstrap the 2nd datacenter nodes (halfway) in between your 1st >> datacenter tokens, so your ring alternates DC1 DC2 DC1 DC2 etc. Do >> this one at a time for minimum disruption. You should have equal node >> counts in each DC because RAS will keep data in each DC about equal. >> - Switch the cluster to RAS >> - Start repair. You will need to run repair on each node. In 0.6 you >> should only run repair against one node at a time. >> - While repair is going on, you need to do reads at at least CL.QUORUM >> or data may appear to be missing, since it's not yet in all the places >> the new strategy will look. (But by alternating DC around the ring, 2 >> of the 3 replicas are guaranteed to be the same for both RUS and RAS.) >> >> The wrong way: >> - Switch to RAS, then start adding nodes in the new DC. As soon as >> you add the first node in DC2, RAS will try to replicate ALL the rows >> in DC1 to it. Usually this overwhelms the DC2 node and it dies a >> fiery death. >> >> On Wed, Jul 27, 2011 at 7:44 PM, Ashley Martens <amart...@ngmoco.com> wrote: >>> I have a current 0.6.x cluster in a single datacenter with RackUnaware and >>> am looking to expand into a second data center. I know I need to change to >>> RackAwareStrategy however, I'm not sure what will happen to my data when I >>> restart the nodes in the current cluster before I even add the new DC. Will >>> the data need to move based on the rack each node is in or will it stay on >>> the node it is currently on? Also, when I start adding nodes in the new DC >>> to the cluster should they come in one at a time, like bootstrap, or should >>> I light up several at the same time to distribute the data? >>> >>> For reference I have 19 nodes in my cluster. >>> >>> Thanks. >>> >> >> >> >> -- >> Jonathan Ellis >> Project Chair, Apache Cassandra >> co-founder of DataStax, the source for professional Cassandra support >> http://www.datastax.com > -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com
