# 2 Node cluster questions **URL:** \ **Category:** Elasticsearch\ **Created:** [January 8, 2018, 11:37am UTC](https://discuss.elastic.co/t/2-node-cluster-questions/114510 "2018-01-08T11:37:07Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![cosmo](https://avatars.discourse-cdn.com/v4/letter/c/46a35a/32.png) [@cosmo](https://discuss.elastic.co/u/cosmo)\ **Post date:** [January 8, 2018, 11:37am UTC](https://discuss.elastic.co/t/2-node-cluster-questions/114510/1 "2018-01-08T11:37:07Z")
Hello Appreciate this topic has lots of topics already, but I have a few specific (but general) questions; **Use case:** Web logs, cron logs, other logs into an elastic stack so devs can look at logs, spot problems etc. 100% availability not required, but would be annoying to reindex all the logs again from scratch. Sort of unrelated - also want somewhere to run jenkins and tests **Current situation** 1 Machine running full elastic stack (elastic/kibana/logstash) & Jenkins, selenium and some other tools. Jenkins is slow when elastic is doing stuff, and visa versa, so everything is just generally slow ☹ I have 4 indexes, all now setup as 1 shard (and one replia), for a daily period. (might change this to weekly for some indexes as each shard doesn't hold much data (50mb). **Proposal** As this is just for internal dev, don't have a super huge budget 💸 I am thinking about setting up 2 machines, like the pretty picture on [the add failover guide](https://www.elastic.co/guide/en/elasticsearch/guide/current/_add_failover.html) [![](https://www.elastic.co/guide/en/elasticsearch/guide/current/images/elas_0203.png) ](https://www.elastic.co/guide/en/elasticsearch/guide/current/images/elas_0203.png) _Machine 1_ - elastic master & data - kibana - logstash - jenkins slave _Machine 2_ - elastic data (replica) - jenkins master - other testing tools Fully appreciate it is not recommended to run a 2 node elastic cluster, but can't really justify another machine just to make elastic happy, so; 1 master to stop split brain situation. We're not too fussed if master dies for a little bit, so long as we can get it back manually in a 'reasonable' amount of time **Question 1:** Say machine 1 blows up. Can I do the following, and will it work as I think it will? I promote machine 2 to a master temporarily (replica shard happy to turn into primaries?), then setup a new machine 1 as a data only node. Data is then replicated across. I then stop machine 2, make machine 1 a master, reset machine 2 back to data only. Everyone is happy, machine 1 is master, machine 2 is data replica and don't have to reindex all logs? **Question 2:** Kibana - I set this to talk to machine 1. Will elastic on machine 1 work out that there is a data node it can talk to as so share out some of the work? **Question 3:** Rolling upgrades - I just upgrade master as per docs, then data only. Everything happy? Full cluster restart - I stop master and data, upgrade master, then data. Everything happy? Many thanks! ---
**Author:** ![luiz.santos](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/luiz.santos/32/24664_2.png) [@luiz.santos](https://discuss.elastic.co/u/luiz.santos)\ **Post date:** [January 9, 2018, 12:48pm UTC](https://discuss.elastic.co/t/2-node-cluster-questions/114510/2 "2018-01-09T12:48:20Z")
Hi @cosmo, I will answer your question based on your statement that this is not a production bulletproof cluster. Question 1: Instead of doing all these changes if a node fails I would let both nodes be master/data nodes and set [minimum\_master\_nodes: 2](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-node.html#split-brain). If one node fails elasticsearch cluster will reject indexing documents. Then you can either take some action to have 2 nodes again or set minimum\_master\_nodes: 1 temporarily until the second node is up again. This can be done through REST API. If you do the way you are proposing I think it will work too, but it's more error-prone. Question 2: In this case, all request will arrive in machine 1 but elasticsearch will distribute processing across both nodes. A better solution would be [load balancing](https://www.elastic.co/guide/en/kibana/current/production.html#load-balancing) but as you said you don't want to add more nodes.... Question 3: Both rolling upgrade and full restart will work 🙂 Hope it helps. Cheers, Luiz Santos ---
**Author:** ![cosmo](https://avatars.discourse-cdn.com/v4/letter/c/46a35a/32.png) [@cosmo](https://discuss.elastic.co/u/cosmo)\ **Post date:** [January 10, 2018, 2:21pm UTC](https://discuss.elastic.co/t/2-node-cluster-questions/114510/3 "2018-01-10T14:21:54Z")
Thanks Luiz! I'll look at having them both Master/data nodes then. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [February 7, 2018, 2:22pm UTC](https://discuss.elastic.co/t/2-node-cluster-questions/114510/4 "2018-02-07T14:22:24Z")
This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.