Well, scaling down is straightforward: in that case, you *are* taking down the node (or at least, the ActorSystem), so you should down it. As soon as you down it, the shards should migrate properly to other nodes. That's normal stuff. Keep in mind that "unreachable but not down" should be a *temporary* situation -- your system should be built to properly down the unreachable node before long. (With the appropriate precautions against split-brain.)
Rolling out a new version of your application without stopping *is* tricky. At the moment, I'm accepting very brief downtime (a few seconds) to shut down the old cluster and boot the new one. Doing a proper rolling release seems plausible, but you have to think carefully about wire compatibility between the nodes. I don't know offhand of a simple way to do a rolling release if the wire protocols aren't compatible -- at that point, I think you have to have application complicity in the process, and it probably has to be handled with a lot of care... On Mon, Feb 27, 2017 at 2:24 PM, Andrey Ilinykh <ailin...@gmail.com> wrote: > > > On Monday, February 27, 2017 at 10:11:59 AM UTC-8, Justin du coeur wrote: >> >> There's no silver-bullet option for "fault tolerance" in situations like >> this. You absolutely do *not* want to start up alternate versions of the >> sharded entities in this situation -- that's classic split-brain, and is >> the surest route to data corruption. >> > yes, this is a dangerous route. But what is the a way to manage cluster? I > mean roll out of a new version or scaling down. In such situations one has > to stop akka (or whole node). > > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: http://doc.akka.io/docs/akka/ > current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
