# What are ilm-history and slm-history indices used for? **URL:** \ **Category:** Elasticsearch\ **Tags:** ilm-index-lifecycle-management, slm-snapshot-lifecycle-management\ **Created:** [May 26, 2022, 12:36pm UTC](https://discuss.elastic.co/t/what-are-ilm-history-and-slm-history-indices-used-for/305711 "2022-05-26T12:36:31Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![leandrojmp](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/leandrojmp/32/107231_2.png) [@leandrojmp](https://discuss.elastic.co/u/leandrojmp)\ **Post date:** [May 26, 2022, 12:36pm UTC](https://discuss.elastic.co/t/what-are-ilm-history-and-slm-history-indices-used-for/305711/1 "2022-05-26T12:36:31Z")
I'm doing some cleanup on my cluster and saw that there are a couple of small system indices that I'm not sure for what they are used. Those indices are mostly `ilm-history-*` , `.ds-ilm-history-*` , `.slm-history-*` and `.ds-slm-history`. As the name made it clear, they are associated to the Index Lifecycle Management and Snapshot Lifecycle Management, but I'm not sure what is the use or if I can remove them. One of most repeated recomendations from Elastic is to avoid to have lot of small indices and yet the Elasticsearch itself keeps creating those small indices. Both `slm-history-ilm-policy` and `ilm-history-ilm-policy` are using the default settings for rollover with 30 days or 50 GB, the `slm-history-ilm-policy` has a delete phase after 90 days, but the `ilm-history-ilm-policy` does not have a delete phase. My question is, what are these indices used for? It is safe to change the delete phase for something like 1 or 2 days? ---
**Author:** ![leandrojmp](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/leandrojmp/32/107231_2.png) [@leandrojmp](https://discuss.elastic.co/u/leandrojmp)\ **Post date:** [May 26, 2022, 2:25pm UTC](https://discuss.elastic.co/t/what-are-ilm-history-and-slm-history-indices-used-for/305711/2 "2022-05-26T14:25:42Z")
About `ilm-history` there is not much in the documentation. I was able to find this [part](https://www.elastic.co/guide/en/elasticsearch/reference/8.2/ilm-settings.html) on how to enable it and saying that this is enabled by default. And also this [blog post](https://www.elastic.co/blog/troubleshooting-elasticsearch-ilm-common-issues-and-fixes) saying to use ILM History to troubleshoot ILM Issues, so, the ilm-history indices are only a record of the ilm actions and only exists for troubleshoot issues? For `slm-history` I found just this [part](https://www.elastic.co/guide/en/elasticsearch/reference/8.2/snapshot-settings.html#_slm_settings) telling how to set it and again it is already enabled by default, but I didn't find any explanation about where it is used, I'm assuming that this is used only for troubleshoot issues, is this correct? Will disabling the `ilm-history` and `slm-history` affect the ILM and SLM process? ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [June 23, 2022, 2:26pm UTC](https://discuss.elastic.co/t/what-are-ilm-history-and-slm-history-indices-used-for/305711/3 "2022-06-23T14:26:06Z")
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**Author:** ![Stef\_Nestor](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/stef_nestor/32/85483_2.png) [@Stef\_Nestor](https://discuss.elastic.co/u/Stef_Nestor)\ **Post date:** [November 30, 2024, 9:49pm UTC](https://discuss.elastic.co/t/what-are-ilm-history-and-slm-history-indices-used-for/305711/4 "2024-11-30T21:49:10Z")
> [@leandrojmp](#): > > And also this [blog post](https://www.elastic.co/blog/troubleshooting-elasticsearch-ilm-common-issues-and-fixes) saying to use ILM History to troubleshoot ILM Issues, so, the ilm-history indices are only a record of the ilm actions and only exists for troubleshoot issues? Thanks for the feedback! Confirmed, these indices just record historical ILM+SLM states same as are logged into Elasticsearch logs (so can be disabled if desired without disabling either feature). From your feedback (thanks!), I've expanded related ILM content from my earlier linked blog: - blog: [Monitoring Elasticsearch index lifecycle management with the history index](https://www.elastic.co/blog/elasticsearch-index-lifecycle-management-history-index) - video: [ILM Health | History Index | Elastic Cloud | Support Troubleshooting](https://www.youtube.com/watch?v=onrnnwjYWSQ)