@Rob: Thanks about the feedback. Yet I have a weird behavior still unexplained about repairing. Are counters supposed to be "repaired" too ? I mean, while reading at CL.ONE I can have different values depending on what node is answering. Even after a read repair or a full repair. Shouldn't a repair fix these discrepancies ?
The only way I found to get always the same count is to read data at CL.QUORUM, but this is a workaround since the data itself remains wrong on some nodes. Any clue on it ? Alain 2013/5/15 Edward Capriolo <edlinuxg...@gmail.com> > http://basho.com/introducing-riak-1-3/ > > Introduced Active Anti-Entropy. Riak now has active anti-entropy. In > distributed systems, inconsistencies can arise between replicas due to > failure modes, concurrent updates, and physical data loss or corruption. > Pre-1.3 Riak already had several features for repairing this “entropy”, but > they all required some form of user intervention. Riak 1.3 introduces > automatic, self-healing properties that repair entropy on an ongoing basis. > > > On Wed, May 15, 2013 at 5:32 PM, Robert Coli <rc...@eventbrite.com> wrote: > >> On Wed, May 15, 2013 at 1:27 AM, Alain RODRIGUEZ <arodr...@gmail.com> >> wrote: >> > Rob, I was wondering something. Are you a commiter working on improving >> the >> > repair or something similar ? >> >> I am not a committer [1], but I have an active interest in potential >> improvements to the best practices for repair. The specific change >> that I am considering is a modification to the default >> gc_grace_seconds value, which seems picked out of a hat at 10 days. My >> view is that the current implementation of repair has such negative >> performance consequences that I do not believe that holding onto >> tombstones for longer than 10 days could possibly be as bad as the >> fixed cost of running repair once every 10 days. I believe that this >> value is too low for a default (it also does not map cleanly to the >> work week!) and likely should be increased to 14, 21 or 28 days. >> >> > Anyway, if a commiter (or any other expert) could give us some feedback >> on >> > our comments (Are we doing well or not, whether things we observe are >> normal >> > or unexplained, what is going to be improved in the future about >> repair...) >> >> 1) you are doing things according to best practice >> 2) unfortunately your experience with significantly degraded >> performance, including a blocked go-live due to repair bloat is pretty >> typical >> 3) the things you are experiencing are part of the current >> implementation of repair and are also typical, however I do not >> believe they are fully "explained" [2] >> 4) as has been mentioned further down thread, there are discussions >> regarding (and some already committed) improvements to both the >> current repair paradigm and an evolution to a new paradigm >> >> Thanks to all for the responses so far, please keep them coming! :D >> >> =Rob >> [1] hence the (unofficial) tag for this thread. I do have minor >> patches accepted to the codebase, but always merged by an actual >> committer. :) >> [2] driftx@#cassandra feels that these things are explained/understood >> by core team, and points to >> https://issues.apache.org/jira/browse/CASSANDRA-5280 as a useful >> approach to minimize same. >> > >
