So let me take a few steps back and put forth a use-case which might throw some light on what I am pursuing.
Lets say I have 3 nodes A, B and C and I want to create a peer-peer cluster so that all of them join a cluster (like the jgroups model). I then want to add resources to A or B or C and expect the specific node to push the resource information to the cluster based on the resource's replication strategy. So lets say X is installed on A and X states I want to be available on exactly 2 nodes then I imagine the cluster will pick two of A, B or C to hold the resource. So a few questions, please bear with my ignorance * In this use-case a good fit for Helix, I would love to get the replication strategy through Helix but if I am dealing with a inherent master-slave model which is not peer-peer am I using Helix for the wrong thing? * Do all install requests get routed to the Master and then pushed to the relevant slaves? Thanks, Sandeep On Thu, Feb 20, 2014 at 1:07 PM, Kanak Biscuitwala <[email protected]> wrote: > Are you talking about the controller or the participants (instances)? If you > would like to see if the controller is running, check under > /clusterName/CONTROLLER to see if there is a ZNode called LEADER. > > For participants, nothing will be assigned until resources are defined. Ideal > states and external views are created and used on a per-resource level. Helix > can manage multiple distributed resources at once, so you need to add a > resource to define things like the state model it follows, the assignment > policy (rebalance mode), and number of partitions and replicas. This step > generates the ideal state for the resource. The quickstart and tutorial > detail these steps. > > Kanak > ---------------------------------------- >> Date: Thu, 20 Feb 2014 12:53:08 -0800 >> Subject: Re: Helix 0.6.2- Messages on startup >> From: [email protected] >> To: [email protected] >> >> Thanks Jason for the pointers. I do see the nodes and InstanceConfigs >> but there is no indication of which is master, do I need to add >> resources to the cluster for that information to surface? If nodes are >> added to the cluster should I be able to see which is the master or >> leader and which are the followers? >> >> Sandeep >> >> On Thu, Feb 20, 2014 at 11:51 AM, Zhen Zhang <[email protected]> wrote: >>> For checking external-view, you can use zoo inspector: >>> http://helix.apache.org/0.7.0-incubating-docs/Quickstart.html >>> >>> The zookeeper path is for the external view is >>> /{clusterName}/{externalView}/{resourceName} >>> >>> If you want do it programmatically, you can use spectator: >>> http://helix.apache.org/0.7.0-incubating-docs/tutorial_spectator.html >>> >>> >>> The time for a node to transit to its target state depends on how long the >>> state transition takes. >>> >>> In normal case, if the external-view matches the ideal-state, it indicates >>> the cluster converges. >>> >>> Thanks, >>> Jason >>> >>> On 2/20/14 11:29 AM, "Sandeep Nayak" <[email protected]> wrote: >>> >>>>I probably missed it in the documentation, but how can I check the >>>>external view? Also, is there a time period after which the first node >>>>logs that it has identified itself as the leader? Just wanted to know >>>>what is the indicator that things work and I do have a leader and >>>>follower in the cluster? >>>> >>>>Thanks, >>>> >>>>Sandeep >>>> >>>>On Thu, Feb 20, 2014 at 9:34 AM, Kanak Biscuitwala <[email protected]> >>>>wrote: >>>>> We didn't, but now we do. >>>>> ________________________________ >>>>>> Date: Thu, 20 Feb 2014 09:26:10 -0800 >>>>>> Subject: Re: Helix 0.6.2- Messages on startup >>>>>> From: [email protected] >>>>>> To: [email protected] >>>>>> >>>>>> Do we have a jira for this ? >>>>>> >>>>>> >>>>>> On Wed, Feb 19, 2014 at 11:20 PM, Kanak Biscuitwala >>>>>> <[email protected]<mailto:[email protected]>> wrote: >>>>>> Hi Sandeep, >>>>>> >>>>>> Does Helix still generate an external view correctly despite these log >>>>>> messages? >>>>>> >>>>>> I believe the first message is a known issue: the callbacks are >>>>>> initialized once by the HelixManager implementation, and then >>>>>> initialized again when the controller becomes leader (for the first >>>>>> controller, these will happen very close to one another). It's >>>>>> generally a harmless message. >>>>>> >>>>>> The second one indicates that the controller is getting events (which >>>>>> path was changed to trigger the event?), but hasn't yet become leader. >>>>>> When it does, it will invoke the pipeline and do the right thing. >>>>>> >>>>>> I think in either case, a race is causing the log messages to appear, >>>>>> but it shouldn't affect the correctness of the Helix controller >>>>>> operation. >>>>>> >>>>>> Kanak >>>>>> >>>>>> Date: Wed, 19 Feb 2014 23:13:19 -0800 >>>>>> Subject: Helix 0.6.2- Messages on startup >>>>>> From: [email protected]<mailto:[email protected]> >>>>>> To: [email protected]<mailto:[email protected]> >>>>>> >>>>>> Hi guys, >>>>>> >>>>>> So I finally got my setup done with states etc. But when I start the >>>>>> first node I see the following messages >>>>>> >>>>>> expected types: [CALLBACK, FINALIZE] but was INIT >>>>>> I see this for /cluster/Controller, >>>>>> /cluster/INSTANCES/Instance/MESSAGES and several other paths. >>>>>> The other message I see is >>>>>> Cluster manager: first-node is not leader. Pipeline will not be invoked >>>>>> Any ideas on what I am missing here? >>>>>> Thanks, >>>>>> Sandeep >>>>>> >>>
