Prevent setting minimum_master_nodes to more than the current node count

Elastic Stack Elasticsearch
1

Setting zen.discovery.minimum_master_nodes to a value higher than the current node count effectively leaves the cluster without a master and unable to process requests.

The official website below has fixed this bug.
https://www.elastic.co/guide/en/elasticsearch/resiliency/current/index.html

The official version 1.5.0 fixed this defect by adding verification, which does not solve this problem in my opinion. When a node in the cluster exits due to a crash, the cluster still cannot elect a new master. I verified this on version 1.5.0. Set discovery.zen.minimum_master_nodes:3, start a cluster of 3 nodes and run normally, shut down one node to simulate its crash, and then poll another node to access its status, the results are as follows:

"status" : 503,
  "name" : "node-0",
  "cluster_name" : "es-clusters",
  "version" : {
    "number" : "1.5.0",
    "build_hash" : "581bcd3deec6302b0a0a6ac3935556400efbce15",
    "build_timestamp" : "2023-02-27T02:46:06Z",
    "build_snapshot" : false,
    "lucene_version" : "4.10.4"
  },
  "tagline" : "You Know, for Search"

Obviously the cluster cannot elect a new master, I can see not enough master nodes in es-clusters.log.

In addition, when discovery.zen.minimum_master_nodes > 3 is set when starting the cluster, the cluster cannot start normally, but there is no feedback error in the log, but print started.

2

The version you are using to is very, very old and have been EOL a long time. The setting you are referring to was removed in version 7.0 and the cluster now handles it automatically. I would recommend you upgrade to the latest version.

3

Thank you for your reply. I accidentally noticed this bug and tested it. From a testing standpoint, this may have been problematic at the time.

4

Note that the version you tested came out almost 8 years ago and have been EOL for almost as long.

5

Yeah, the only solution to this is to upgrade to a version that is supported. You will never see a patch for this version.

6

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