Re: [infinispan-dev] design for cluster events (wiki page)

On 10/31/13 4:45 PM, Dennis Reed wrote: > On 10/31/2013 02:18 AM, Bela Ban wrote: >> >>> Also if we did have read only, what criteria would cause those nodes >>> to be writeable again? >> Once you become the primary partition, e.g. when a view is received >> where view.size() >= N where N is a predefined threshold. Can be >> different, as long as it is deterministic. >> >>> There is no guarantee when the other nodes >>> will ever come back up or if there will ever be additional ones anytime soon. >> If a system picks the Primary Partition approach, then it can become >> completely inaccessible (read-only). In this case, I envisage that a >> sysadmin will be notified, who can then start additional nodes for the >> system to acquire primary partition and become accessible again. > > There should be a way to manually modify the primary partition status. > So if the admin knows the nodes will never return, they can manually > enable the partition. > > Also, the PartitionContext should know whether the nodes left normally > or not. > If you have 5 nodes in a cluster, and you shut down 3 of them, you'll > want the remaining two to remain available. > But if there was a network partition, you wouldn't. So it needs to know > the difference. JGroups won't tell you, and I don't want to add a flag to each member of a view telling you whether it was a graceful or crash-leave. However, you (Infinispan) could send a LEAVE message shortly before leaving, which is stored by everyone (or only the coord?). When the view is received, we should be able to determine who left and who crashed.