What happens if 2 of 5 data nodes are down?

Elastic Stack Elasticsearch
1

Dear community,
what does happen if in an Elasticsearch cluster 2 of 5 data nodes are down, data is still incoming via logstash and daily indices are used (cluster version 7.8.1)? For example the nodes are down for max 1hour and then come back online?
By the way: in the Elasticsearch.yml I have also this in place:

gateway.recover_after_data_nodes: 4
gateway.recover_after_master_nodes: 2
gateway.recover_after_time: 4m
gateway.expected_master_nodes: 3
gateway.expected_data_nodes: 5

Should I chage gateway.recover_after_data_nodes to 3??

Thank you very much for your / any insight!
cheers
Ste

2

7.8 is nearly EOL, you should look to upgrade if you can. 7.15 is latest.

Basically it'll rebalance the indices and continue on. If you know the nodes are coming back you can always look at altering Delaying allocation when a node leaves | Elasticsearch Guide [7.15] | Elastic.

You can change that dynamically, which might be a better option if you know it's short term.

3

Thank you very much for your insights!
cheers
Stefano

4

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