I had the exact same question, but I think this is what Nate was thinking: If you're running multiple nodes on a single server, vnodes give you no control over which instance has which key (whereas you can assign initial tokens). Therefore you could have two of your three replicas on the same physical server which, if it goes down, you can't read or write at quorum.
However, can't you use the topology snitch to put both nodes in the same rack? Won't that prevent the issue and still allow you to maintain quorum if a single server goes down? If I have a 20-node cluster with 2 nodes on each physical server, can I use 10 racks to properly segment my partitions? On Sun, May 24, 2015 at 5:38 PM, Jonathan Haddad <j...@jonhaddad.com> wrote: > What impact would vnodes have on strong consistency? I think the problem > you're describing exists with or without them. > > On Sat, May 23, 2015 at 2:30 PM Nate McCall <n...@thelastpickle.com> > wrote: > >> >>> So my question is: suppose I take a 12 disk JBOD and run 2 Cassandra >>> nodes (each with 5 data disks, 1 commit log disk) and either give each its >>> own container & IP or change the listen ports. Will this work? What are the >>> risks? Will/should Cassandra support this better in the future? >>> >> >> Don't use vnodes if any operations need strong consistency (reading or >> writing at quorum). Otherwise, at RF=3, if you loose a single node you will >> only have one 1 replica left for some portion of the ring. >> >> >> >> -- >> ----------------- >> Nate McCall >> Austin, TX >> @zznate >> >> Co-Founder & Sr. Technical Consultant >> Apache Cassandra Consulting >> http://www.thelastpickle.com >> > -- *Ken Hancock *| System Architect, Advanced Advertising SeaChange International 50 Nagog Park Acton, Massachusetts 01720 ken.hanc...@schange.com | www.schange.com | NASDAQ:SEAC <http://www.schange.com/en-US/Company/InvestorRelations.aspx> Office: +1 (978) 889-3329 | [image: Google Talk:] ken.hanc...@schange.com | [image: Skype:]hancockks | [image: Yahoo IM:]hancockks[image: LinkedIn] <http://www.linkedin.com/in/kenhancock> [image: SeaChange International] <http://www.schange.com/>This e-mail and any attachments may contain information which is SeaChange International confidential. The information enclosed is intended only for the addressees herein and may not be copied or forwarded without permission from SeaChange International.
