# What will be cached by disk filesystem cache?

**URL:** <https://discuss.elastic.co/t/what-will-be-cached-by-disk-filesystem-cache/146119>\
**Category:** Elasticsearch\
**Created:** [August 27, 2018, 7:09am UTC](https://discuss.elastic.co/t/what-will-be-cached-by-disk-filesystem-cache/146119 "2018-08-27T07:09:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![bruce88](https://avatars.discourse-cdn.com/v4/letter/b/b3f665/32.png) [@bruce88](https://discuss.elastic.co/u/bruce88)\
**Post date:** [August 27, 2018, 7:09am UTC](https://discuss.elastic.co/t/what-will-be-cached-by-disk-filesystem-cache/146119/1 "2018-08-27T07:09:34Z")

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We know that it's better to make sure that at least half the available memory goes to the filesystem cache so that Elasticsearch can keep hot regions of the index in physical memory. And in the \_nodes/stats API, we can get some metrics about segments memory. Except these items, what else will be cached by disk filesystem cache?

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**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [August 27, 2018, 7:49am UTC](https://discuss.elastic.co/t/what-will-be-cached-by-disk-filesystem-cache/146119/2 "2018-08-27T07:49:31Z")

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That's entirely up to the OS to manage, so it could be anything.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [September 24, 2018, 7:49am UTC](https://discuss.elastic.co/t/what-will-be-cached-by-disk-filesystem-cache/146119/3 "2018-09-24T07:49:46Z")

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