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.
