I'ts 2 out of the number of replicas, not the number of nodes. At RF=2, you have 2 replicas. And since quorum is also 2 with that replication factor, you cannot lose a node, otherwise some query will end up as UnavailableException.
Again, this is not related to the total number of nodes. Even with 200 nodes, if you use RF=2, you will have some query that fail (altough much less that what you are probably seeing). On Thu, Dec 9, 2010 at 5:00 PM, Timo Nentwig <timo.nent...@toptarif.de> wrote: > > On Dec 9, 2010, at 16:50, Daniel Lundin wrote: > >> Quorum is really only useful when RF > 2, since the for a quorum to >> succeed RF/2+1 replicas must be available. > > 2/2+1==2 and I killed 1 of 3, so... don't get it. > >> This means for RF = 2, consistency levels QUORUM and ALL yield the same >> result. >> >> /d >> >> On Thu, Dec 9, 2010 at 4:40 PM, Timo Nentwig <timo.nent...@toptarif.de> >> wrote: >>> Hi! >>> >>> I've 3 servers running (0.7rc1) with a replication_factor of 2 and use >>> quorum for writes. But when I shut down one of them UnavailableExceptions >>> are thrown. Why is that? Isn't that the sense of quorum and a >>> fault-tolerant DB that it continues with the remaining 2 nodes and >>> redistributes the data to the broken one as soons as its up again? >>> >>> What may I be doing wrong? >>> >>> thx >>> tcn > >
