From: http://www.datastax.com/dev/blog/modern-hinted-handoff Repair and the fine print
At first glance, it may appear that Hinted Handoff lets you safely get away without needing repair. This is only true if you never have hardware failure. Hardware failure means that 1. We lose “historical” data for which the write has already finished, so there is nothing to tell the rest of the cluster exactly what data has gone missing 2. We can also lose hints-not-yet-replayed from requests the failed node coordinated With sufficient dedication, you can get by with “only run repair after hardware failure and rely on hinted handoff the rest of the time,” but as your clusters grow (and hardware failure becomes more common) performing repair as a one-off special case will become increasingly difficult to do perfectly. Thus, we continue to recommend running a full repair weekly. 2015-03-19 16:42 GMT-03:00 Robert Coli <rc...@eventbrite.com>: > On Thu, Mar 19, 2015 at 12:13 PM, Ali Akhtar <ali.rac...@gmail.com> wrote: > >> Cassandra doesn't guarantee eventual consistency? >> > > If you run regularly scheduled repair, it does. If you do not run repair, > it does not. > > Hinted handoff, for example, is considered an optimization for repair, and > does not assert that it provides a consistency guarantee. > > =Rob > http://twitter.com/rcolidba > -- Paulo Ricardo -- European Master in Distributed Computing *Royal Institute of Technology - KTH* *Instituto Superior Técnico - IST* *http://paulormg.com <http://paulormg.com>*
