I haven't found any guidelines on setting the max_num_segments for force merge. For instance, we have weekly indexes at about 120GB each with 4 primary shards, how to deternmine the proper max_num_segments when running force merge on those indexes?
for your use case the optimal number is 1. Force merging is very I/O intensive but if you don't write to this index after force merge (and that's the case here with hot/cold), then Lucene needs to search in only one segment and you also need to do the force merge once.
Thanks @danielmitterdorfer. From one of the videos in ElasticON 2016, a support engineer recommended that the size of each shard should be under 50 GB. Would it also be the recommended size for a Lucene segment?
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