Hi Michael,
Some more questions: 1. Can I set the grid active once all primaries are active, but before all backups are active? Or do I need to have the entire cluster running before setting active to true? 2. Is there an assumption that the cluster size is static and known at the time of startup/restart? If so, how are dynamic clusters that grow and shrink according to demand catered for? 3. Is it usually the responsibility of one of the cluster nodes to set active to true, or is it the responsibility of an external client server node on the grid to detect the point at which the cluster running correctly and set active to true? If a cluster type node is used, does this result in a swarm of activation messages as each node inspects the latest topology changed event and sets active to true? Thanks, Raymond. *From:* Michael Cherkasov [mailto:michael.cherka...@gmail.com] *Sent:* Thursday, August 3, 2017 9:27 PM *To:* user@ignite.apache.org *Subject:* Re: Best practise for setting Ignite.Active to true when using persistence layer in Ignite 2.1 Hi Raymond, Unfortunately right now there's no auto-activation, restarting cluster is like rare event that should be controlled manually. However you can listen for EVT_NODE_JOINED event, when all nodes in place you can activate a cluster. And you only need this if you have ignite persistence turn on and you have some data on the disk. Thanks, Mikhail. 2017-08-03 6:58 GMT+03:00 Raymond Wilson <raymond_wil...@trimble.com>: Michael, Is there a reference implementation in Ignite 2.1 for an agent that listens to topology changes to decide when to set active to true? Thanks, Raymond. *From:* Michael Cherkasov [mailto:michael.cherka...@gmail.com] *Sent:* Thursday, August 3, 2017 1:25 AM *To:* user@ignite.apache.org *Subject:* Re: Best practise for setting Ignite.Active to true when using persistence layer in Ignite 2.1 >Does this mean we have to listen to events of server nodes going up and down and activate and deactivate the cluster? No, you need to deactivate cluster when you going to shutdown the whole cluster. And when you return cluster back to online, you need to wait when all nodes are in place and then activate it. 2017-08-02 16:22 GMT+03:00 Rohan Shetty <rohan.she...@gmail.com>: Does this mean we have to listen to events of server nodes going up and down and activate and deactivate the cluster? On Wed, Aug 2, 2017 at 3:18 PM, Michael Cherkasov < michael.cherka...@gmail.com> wrote: when all nodes are up, so in latest topology snapshot you can see servers count == servers count you run, then cluster can be activated. 2017-08-02 0:51 GMT+03:00 Raymond Wilson <raymond_wil...@trimble.com>: Hi Mikhail, Thanks for the clarifications. Yes, I knew setting active was only required when using the persistence layer, which is the topic of the question J I was interested if there were best practices or approaches for determining when the grid had fully initialized. I realise this is somewhat application specific, but was looking for an established pattern before I invented one myself. In my case I have an affinity function that responds to topology changes which intrinsically would know when it had a ‘quorum’. Is this a typical place for setting active to true. Thanks, Raymond. *From:* Mikhail Cherkasov [mailto:mcherka...@gridgain.com] *Sent:* Tuesday, August 1, 2017 11:59 PM *To:* user@ignite.apache.org *Subject:* Re: Best practise for setting Ignite.Active to true when using persistence layer in Ignite 2.1 Hi Raymond, Ignite cluster is inactive on startup only if persistence is enabled. This is done to avoid unnecessary partition exchanges between nodes, for example, if you have 3 nodes and 1 backup enabled and you start only 2 of 3 nodes, then they will treat the third node as dead and start process of restoring data from backup and rebalance data to spread them among 2 nodes, when you add the missed third node back the process will be repeated. So we start cluster as in active. When all nodes are started and ready, so no cluster topology changes aren't expected, you should activate cluster. Also when you turn off cluster, some nodes can still accept request for data update and other nodes won't see it, so understand which node has the latest data we need to start all nodes first and only then activate cluster. Thanks, Mikhail. On Tue, Aug 1, 2017 at 5:05 AM, Raymond Wilson <raymond_wil...@trimble.com> wrote: Hi, I am experimenting with a POC looking into using the Ignite persistence layer. One aspect of this is setting the grid to be ‘Active’ after all cache grid nodes have instantiated. In practical terms, what is the best practice for ensuring the cluster is running and in a good state to be set to active? What is the downside of setting active to true before all grid nodes are running? Thanks, Raymond. -- Thanks, Mikhail.
