# System index responsible for \_cat/shards **URL:** \ **Category:** Elasticsearch\ **Created:** [August 8, 2022, 10:50pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678 "2022-08-08T22:50:07Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![kossde](https://avatars.discourse-cdn.com/v4/letter/k/f19dbf/32.png) [@kossde](https://discuss.elastic.co/u/kossde)\ **Post date:** [August 8, 2022, 10:50pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/1 "2022-08-08T22:50:07Z")
Can anyone tell me which indices are responsible for the data pulled in when using the \_cat/shards API? ---
**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 8, 2022, 11:48pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/2 "2022-08-08T23:48:09Z")
It's from the cluster stats - [Cluster state API | Elasticsearch Guide [8.3] | Elastic](https://www.elastic.co/guide/en/elasticsearch/reference/8.3/cluster-state.html) ---
**Author:** ![kossde](https://avatars.discourse-cdn.com/v4/letter/k/f19dbf/32.png) [@kossde](https://discuss.elastic.co/u/kossde)\ **Post date:** [August 8, 2022, 11:55pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/3 "2022-08-08T23:55:15Z")
Sure but I would assume there is an index somewhere storing this information? If so - what's the name of that index? If there is no index, how is the data stored for retrieval in a timely manner? ---
**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 8, 2022, 11:57pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/4 "2022-08-08T23:57:17Z")
Cluster state is not an index, it's internal but it's actually stored on disk of each node. ---
**Author:** ![kossde](https://avatars.discourse-cdn.com/v4/letter/k/f19dbf/32.png) [@kossde](https://discuss.elastic.co/u/kossde)\ **Post date:** [August 9, 2022, 5:39pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/5 "2022-08-09T17:39:26Z")
Could you tell me where the size of the shards are retrieved from? ---
**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 9, 2022, 10:20pm UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/6 "2022-08-09T22:20:51Z")
Probably cluster state as well, but I don't know for sure. ---
**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:** [August 10, 2022, 6:27am UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/7 "2022-08-10T06:27:50Z")
`GET _cat/shards` actually reaches out to all the nodes in the cluster to ask them about the shards they hold and their current sizes. This information isn't stored anywhere, it's obtained afresh each time you call the API. ---
**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 10, 2022, 7:36am UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/8 "2022-08-10T07:36:36Z")
Oh, great to know! ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [September 7, 2022, 7:36am UTC](https://discuss.elastic.co/t/system-index-responsible-for-cat-shards/311678/9 "2022-09-07T07:36:57Z")
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