# Setup one ILM merge task at a time

**URL:** <https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715>\
**Category:** Elasticsearch\
**Tags:** ilm-index-lifecycle-management\
**Created:** [November 9, 2021, 6:39am UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715 "2021-11-09T06:39:40Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![alfianaf](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alfianaf/32/93192_2.png) [@alfianaf](https://discuss.elastic.co/u/alfianaf)\
**Post date:** [November 9, 2021, 6:39am UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/1 "2021-11-09T06:39:40Z")

</div>

Hello, I've been setting up ILM to merge and compress indices,  
but when I checked on stats API

```auto
GET _stats?pretty

```

the result is two merge tasks run concurrently

```auto
      "merges" : {
        "current" : 2,
        "current_docs" : 155120315,
        "current_size_in_bytes" : 16481206343,
        "total" : 46901,
        "total_time_in_millis" : 19245044,
        "total_docs" : 803592602,
        "total_size_in_bytes" : 162075430014,
        "total_stopped_time_in_millis" : 0,
        "total_throttled_time_in_millis" : 6721799,
        "total_auto_throttle_in_bytes" : 86761260455
      }      

```

Is there any way to limit the max concurrent merge task so my cluster performance won't affect by the current task, or is this expected behavior?  
what if my cluster has hundred of indices running same ILM policy so those indices runs hundred merge tasks concurrently

hope I get explanation about this one, thanks in advance

---

<div class="post-metadata">

**Author:** ![alfianaf](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alfianaf/32/93192_2.png) [@alfianaf](https://discuss.elastic.co/u/alfianaf)\
**Post date:** [November 9, 2021, 7:31am UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/2 "2021-11-09T07:31:30Z")

</div>

This is the policy I applied on multiple indices, and ofc this is only a test policy, which leads to the concurrent merge tasks

```auto
PUT _ilm/policy/compression_test
{
  "policy": {
    "phases": {
      "hot": {
        "min_age": "0ms",
        "actions": {
          "set_priority": {
            "priority": 100
          }
        }
      },
      "warm": {
        "min_age": "1ms",
        "actions": {
          "forcemerge": {
            "max_num_segments": 1,
            "index_codec": "best_compression"
          },
          "set_priority": {
            "priority": 50
          },
          "shrink": {
            "number_of_shards": 1
          }
        }
      }
    }
  }
}

```

feel free to ask for additional information about my case, because I have no clue what's further information should I provide

---

<div class="post-metadata">

**Author:** ![alfianaf](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alfianaf/32/93192_2.png) [@alfianaf](https://discuss.elastic.co/u/alfianaf)\
**Post date:** [November 10, 2021, 2:09am UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/3 "2021-11-10T02:09:06Z")

</div>

anyone have insight about this?

---

<div class="post-metadata">

**Author:** ![DavidTurner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidturner/32/22453_2.png) [@DavidTurner](https://discuss.elastic.co/u/DavidTurner)\
**Post date:** [November 10, 2021, 11:03am UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/4 "2021-11-10T11:03:32Z")

</div>

Merges are usually triggered by indexing, but can also be a force-merge which may be triggered by ILM. However force-merges already run one-at-a-time on each node by default.

---

<div class="post-metadata">

**Author:** ![alfianaf](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alfianaf/32/93192_2.png) [@alfianaf](https://discuss.elastic.co/u/alfianaf)\
**Post date:** [November 10, 2021, 4:45pm UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/5 "2021-11-10T16:45:41Z")

</div>

the stats I sent was from ILM, so does it mean that "two merge tasks" was run on two node?

---

<div class="post-metadata">

**Author:** ![DavidTurner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidturner/32/22453_2.png) [@DavidTurner](https://discuss.elastic.co/u/DavidTurner)\
**Post date:** [November 10, 2021, 5:09pm UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/6 "2021-11-10T17:09:12Z")

</div>

The stats you shared were from `GET _stats` so they are not ILM-specific.

---

<div class="post-metadata">

**Author:** ![alfianaf](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alfianaf/32/93192_2.png) [@alfianaf](https://discuss.elastic.co/u/alfianaf)\
**Post date:** [November 10, 2021, 8:03pm UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/7 "2021-11-10T20:03:35Z")

</div>

I mean, the tasks run automatically from ILM condition

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [December 8, 2021, 8:03pm UTC](https://discuss.elastic.co/t/setup-one-ilm-merge-task-at-a-time/288715/8 "2021-12-08T20:03:36Z")

</div>

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