On Thu, Jan 13, 2011 at 2:32 PM, Mark Moseley <[email protected]> wrote: > On Thu, Jan 13, 2011 at 1:08 PM, Gary Dusbabek <[email protected]> wrote: >> It is impossible to properly bootstrap a new node into a system where >> there are not enough nodes to satisfy the replication factor. The >> cluster as it stands doesn't contain all the data you are asking it to >> replicate on the new node. > > Ok, maybe I'm thinking of replication_factor backwards. I took it to > mean how many nodes would have *full* copies of the whole of the > keyspace's data, in which case with my keyspace with > replication_factor=2 the still-alive node would have 100% of the data > to replicate to the wiped-clean node--in which case all the data would > be there to bootstrap. I was assuming replication_factor=2 in a 2-node > cluster == both nodes having a full replica of the data. Do I have > that wrong? > > What's also confusing is that I did this same test on a clean node > that wasn't clustered yet (which is interesting that it doesn't > complain then about replication_factor > # of nodes), so unless it was > throwing away data as I was inserting it, it'd all be there. > > Is the general rule then that the max. replication factor must be > #_of_nodes-1 then? If replication_factor==#_of_nodes, then if you lost > a box, it seems like your cluster would be toast.
Perhaps the better question would be, if I have a two node cluster and I want to be able to lose one box completely and replace it (without losing the cluster), what settings would I need? Or is that an impossible scenario? In production, I'd imagine a 3 node cluster being the minimum but even there I could see each box having a full replica, but probably not beyond 3.
