Thanks Ryan. So, as Jonathan recommended, we should have RF=3 with Three nodes. So Quorum = 2 so, CL= 2 (or I need the CL to be set to two) and I will not need the downgrading retry policy, in case if my one node goes down.
I can dynamically add a New node to my Cluster. Can I change my RF to 3, dynamically without affecting my nodes ? regards Neha On Tue, Dec 16, 2014 at 10:32 PM, Ryan Svihla <rsvi...@datastax.com> wrote: > > > CL quorum with RF2 is equivalent to ALL, writes will require > acknowledgement from both nodes, and reads will be from both nodes. > > CL one will write to both replicas, but return success as soon as the > first one responds, read will be from one node ( load balancing strategy > determines which one). > > FWIW I've come around to dislike downgrading retry policy. I now feel like > if I'm using downgrading, I'm effectively going to be using that downgraded > policy most of the time under server stress, so in practice that reduced > consistency is the effective consistency I'm asking for from my writes and > reads. > > > > On Tue, Dec 16, 2014 at 10:50 AM, Neha Trivedi <nehajtriv...@gmail.com> > wrote: >> >> Hi Jonathan,QUORUM = (sum_of_replication_factors / 2) + 1, For us Quorum >> = (2/2) +1 = 2. >> >> Default CL is ONE and RF=2 with Two Nodes in the cluster.(I am little >> confused, what is my read CL and what is my WRITE CL?) >> >> So, does it mean that for every WRITE it will write in both the nodes? >> >> and For every READ, it will read from both nodes and give back to client? >> >> DOWNGRADERETRYPOLICY will downgrade the CL if a node is down? >> >> Regards >> >> Neha >> >> On Wed, Dec 10, 2014 at 1:00 PM, Jonathan Haddad <j...@jonhaddad.com> >> wrote: >>> >>> I did a presentation on diagnosing performance problems in production at >>> the US & Euro summits, in which I covered quite a few tools & preventative >>> measures you should know when running a production cluster. You may find >>> it useful: >>> http://rustyrazorblade.com/2014/09/cassandra-summit-recap-diagnosing-problems-in-production/ >>> >>> On ops center - I recommend it. It gives you a nice dashboard. I don't >>> think it's completely comprehensive (but no tool really is) but it gets you >>> 90% of the way there. >>> >>> It's a good idea to run repairs, especially if you're doing deletes or >>> querying at CL=ONE. I assume you're not using quorum, because on RF=2 >>> that's the same as CL=ALL. >>> >>> I recommend at least RF=3 because if you lose 1 server, you're on the >>> edge of data loss. >>> >>> >>> On Tue Dec 09 2014 at 7:19:32 PM Neha Trivedi <nehajtriv...@gmail.com> >>> wrote: >>> >>>> Hi, >>>> We have Two Node Cluster Configuration in production with RF=2. >>>> >>>> Which means that the data is written in both the clusters and it's >>>> running for about a month now and has good amount of data. >>>> >>>> Questions? >>>> 1. What are the best practices for maintenance? >>>> 2. Is OPScenter required to be installed or I can manage with nodetool >>>> utility? >>>> 3. Is is necessary to run repair weekly? >>>> >>>> thanks >>>> regards >>>> Neha >>>> >>> > > -- > > [image: datastax_logo.png] <http://www.datastax.com/> > > Ryan Svihla > > Solution Architect > > [image: twitter.png] <https://twitter.com/foundev> [image: linkedin.png] > <http://www.linkedin.com/pub/ryan-svihla/12/621/727/> > > DataStax is the fastest, most scalable distributed database technology, > delivering Apache Cassandra to the world’s most innovative enterprises. > Datastax is built to be agile, always-on, and predictably scalable to any > size. With more than 500 customers in 45 countries, DataStax is the > database technology and transactional backbone of choice for the worlds > most innovative companies such as Netflix, Adobe, Intuit, and eBay. > >
