OK. To sum up: RF=2 and QUORUM are incompatible (if you want to be able to take a node down).
Right? On Sun, Nov 28, 2010 at 7:59 PM, Jake Luciani <jak...@gmail.com> wrote: > I was wrong on this scenario and I'll explain where I was incorrect. > > Hints are stored for a downed node but they don't count towards meeting a > consistency level. > Let's take 2 scenarios: > > RF=6, Nodes=10 > > If you READ/WRITE with CL.QUORUM you will need 4 alive nodes if one is down > it will still have 4 active replicas to write to, one of these will store a > hint and update the downed node when it comes back. > > RF=2, Nodes=3 > > If you READ/WRITE with CL.QUORUM you need 2 live nodes. If one of these 2 > are down you can't meet the QUORUM level so the write will fail. > > In your scenario your best bet is to update to RF=3, then any two nodes > will accept QUORUM > > Sorry for the confusion, > > -Jake > > On Sun, Nov 28, 2010 at 12:26 PM, David Boxenhorn <da...@lookin2.com>wrote: > >> Thank you, Jake. It does... except that in another context you told me: >> >> Hints only happen when a node is unavailable and you are writing with >> CL.ANY >> If you never write with CL.ANY then you can turn off hinted handoff. >> >> How do I reconcile this? >> >> >> On Sun, Nov 28, 2010 at 7:11 PM, Jake Luciani <jak...@gmail.com> wrote: >> >>> If you read/write data with quorum then you can safely take a node down >>> in this scenario. Subsequent writes will use hinted handoff to be passed to >>> the node when it comes back up. >>> >>> More info is here: http://wiki.apache.org/cassandra/HintedHandoff >>> >>> Does that answer your question? >>> >>> -Jake >>> >>> >>> On Sun, Nov 28, 2010 at 9:42 AM, Ran Tavory <ran...@gmail.com> wrote: >>> >>>> to me it makes sense that if hinted handoff is off then cassandra cannot >>>> satisfy 2 out of every 3rd writes writes when one of the nodes is down >>>> since >>>> this node is the designated node of 2/3 writes. >>>> But I don't remember reading this somewhere. Does hinted handoff affect >>>> David's situation? >>>> (David, did you disable HH in your storage-config? >>>> <HintedHandoffEnabled>false</HintedHandoffEnabled>) >>>> >>>> >>>> On Sun, Nov 28, 2010 at 4:32 PM, David Boxenhorn <da...@lookin2.com>wrote: >>>> >>>>> For the vast majority of my data usage eventual consistency is fine >>>>> (i.e. CL=ONE) but I have a small amount of critical data for which I read >>>>> and write using CL=QUORUM. >>>>> >>>>> If I have a cluster with 3 nodes and RF=2, and CL=QUORUM does that mean >>>>> that a value can be read from or written to any 2 nodes, or does it have >>>>> to >>>>> be the particular 2 nodes that store the data? If it is the particular 2 >>>>> nodes that store the data, that means that I can't even take down one >>>>> node, >>>>> since it will be the mandatory 2nd node for 1/3 of my data... >>>>> >>>> >>>> >>>> >>>> -- >>>> /Ran >>>> >>>> >>> >> >
