# I need help to undertand "GET \<target\>/\_ilm/explain" output for ILM policy phases moving

**URL:** https://discuss.elastic.co/t/i-need-help-to-undertand-get-target-ilm-explain-output-for-ilm-policy-phases-moving/327912
**Category:** Elasticsearch
**Tags:** ilm-index-lifecycle-management
**Created:** [March 17, 2023, 9:22am UTC](https://discuss.elastic.co/t/i-need-help-to-undertand-get-target-ilm-explain-output-for-ilm-policy-phases-moving/327912 "2023-03-17T09:22:19Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![LizardNerd](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lizardnerd/32/118560_2.png) [@LizardNerd](https://discuss.elastic.co/u/LizardNerd)
#### Post date: [March 17, 2023, 9:22am UTC](https://discuss.elastic.co/t/i-need-help-to-undertand-get-target-ilm-explain-output-for-ilm-policy-phases-moving/327912/1 "2023-03-17T09:22:19Z")

</div>

Hi there, I'm fairly new to Elastic Stack. I created an ILM policy for my first data stream, then I ran:

```auto
GET .ds-logs-pfsense.log-default-2023.01.26-000004/_ilm/explain

```

This is the output:

```auto
{
  "indices": {
    ".ds-logs-pfsense.log-default-2023.01.26-000004": {
      "index": ".ds-logs-pfsense.log-default-2023.01.26-000004",
      "managed": true,
      "policy": "opnsense",
      "index_creation_date_millis": 1674756268079,
      "time_since_index_creation": "49.62d",
      "lifecycle_date_millis": 1676052317681,
      "age": "34.62d",
      "phase": "cold",
      "phase_time_millis": 1678644702198,
      "action": "complete",
      "action_time_millis": 1678644702398,
      "step": "complete",
      "step_time_millis": 1678644702398,
      "phase_execution": {
        "policy": "opnsense",
        "phase_definition": {
          "min_age": "30d",
          "actions": {
            "allocate": {
              "number_of_replicas": 0,
              "include": {},
              "exclude": {},
              "require": {}
            },
            "set_priority": {
              "priority": 0
            }
          }
        },
        "version": 3,
        "modified_date_in_millis": 1678300649074
      }
    }
  }
}

```

I need a clarification with the parameters "age" and "time\_since\_index\_creation".

The doc say this ([Explain lifecycle API | Elasticsearch Guide [8.11] | Elastic](https://www.elastic.co/guide/en/elasticsearch/reference/current/ilm-explain-lifecycle.html)):

> The time since the index creation (used for calculating when to rollover the index via the max\_age)

> The age of the index (used for calculating when to enter the next phase)

So, what is the difference between "age" and "time\_since\_index\_creation"?  
Which one do I need to consider to know when my index will pass through ILM policy phases?  
Why "age" and "time\_since\_index\_creation" values are different in my case?

Thank you, kindly be patience, I'm new.

---

<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: [April 14, 2023, 9:22am UTC](https://discuss.elastic.co/t/i-need-help-to-undertand-get-target-ilm-explain-output-for-ilm-policy-phases-moving/327912/2 "2023-04-14T09:22:56Z")

</div>

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