On Thu, Oct 8, 2015 at 9:47 AM, Ajay Garg <ajaygargn...@gmail.com> wrote: > Thanks Eric for the reply. > > > On Thu, Oct 8, 2015 at 1:44 AM, Eric Stevens <migh...@gmail.com> wrote: >> If you're at 1 node (N=1) and RF=1 now, and you want to go N=3 RF=3, you >> ought to be able to increase RF to 3 before bootstrapping your new nodes, >> with no downtime and no loss of data (even temporary). Effective RF is >> min-bounded by N, so temporarily having RF > N ought to behave as RF = N. >> >> If you're starting at N > RF and you want to increase RF, things get >> harrier >> if you can't afford temporary consistency issues. >> > > We are ok with temporary consistency issues. > > Also, I was going through the following articles > https://10kloc.wordpress.com/2012/12/27/cassandra-chapter-5-data-replication-strategies/ > > and following doubts came up in my mind :: > > > a) > Let's say at site-1, Application-Server (APP1) uses the two > Cassandra-instances (CAS11 and CAS12), and APP1 generally uses CAS11 for all > its needs (of course, whatever happens on CAS11, the same is replicated to > CAS12 at Cassandra-level). > > Now, if CAS11 goes down, will it be the responsibility of APP1 to "detect" > this and pick up CAS12 for its needs? > Or some automatic Cassandra-magic will happen? > > > b) > In the same above scenario, let's say before CAS11 goes down, the amount of > data in both CAS11 and CAS12 was "x". > > After CAS11 goes down, the data is being put in CAS12 only. > After some time, CAS11 comes back up. > > Now, data in CAS11 is still "x", while data in CAS12 is "y" (obviously, "y" >> "x"). > > Now, will the additional ("y" - "x") data be automatically > put/replicated/whatever back in CAS11 through Cassandra? > Or it has to be done manually? >
Any pointers, please.... ??? > > If there are easy recommended solutions to above, I am beginning to think > that a 2*2 (2 nodes each at 2 data-centres) will be the ideal setup > (allowing failures of entire site, or a few nodes on the same site). > > I am sorry for asking such newbie questions, and I will be grateful if these > silly questions could be answered by the experts :) > > > Thanks and Regards, > Ajay -- Regards, Ajay
