Throttled merge

Elastic Stack Elasticsearch
1

Hello,

Currently we have an index of 33TB (ES 7.8), 48 shards (16 primary, 32 replicas), two months ago we deleted a lot of documents and we noticed that one of the shards (the primary and the 2 replicas) has a very large size (5TB), looking at the detail of the index I notice that the merge has not been executed for 57 days:

  "merges": {
    "current": 0,
    "current_docs": 0,
    "current_size": "0b",
    "current_size_in_bytes": 0,
    "total": 4203366,
    "total_time": "96.1d",
    "total_time_in_millis": 8311549584,
    "total_docs": 15152680627,
    "total_size": "48.6tb",
    "total_size_in_bytes": 53517052444064,
    "total_stopped_time": "0s",
    "total_stopped_time_in_millis": 0,
    "total_throttled_time": "57.2d",
    "total_throttled_time_in_millis": 4942382248,
    "total_auto_throttle": "5mb",
    "total_auto_throttle_in_bytes": 5242880

Config:

      "index.merge.policy.reclaim_deletes_weight": "2.0",
      "index.merge.scheduler.max_merge_count": "5",
      "index.merge.scheduler.max_thread_count": "2",
      "index.merge.policy.deletes_pct_allowed": "33.0",
      "index.merge.policy.expunge_deletes_allowed": "10.0",
      "index.merge.policy.floor_segment": "2mb",
      "index.merge.policy.max_merge_at_once": "10",
      "index.merge.policy.max_merge_at_once_explicit": "30",
      "index.merge.policy.max_merged_segment": "5gb",
      "index.merge.policy.segments_per_tier": "10.0",
      "index.merge.scheduler.auto_throttle": "true",

The idea is not to force a merge, why is the merge not being executed in Elastic?

2

This is EOL, please upgrade as a matter of urgency as latest 7.X is 7.17 so you are a fair bit behind. I would definitely start there before digging further.

3

It looks like you have overridden the default settings. How did you arrive at these configs? What happens if you revert to the defaults?

4

Hi Christian, this is the default configuration, we do not modify it when creating the index.

5

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