# High ReadThroughput and Search is very slow

**URL:** <https://discuss.elastic.co/t/high-readthroughput-and-search-is-very-slow/145999>\
**Category:** Elasticsearch\
**Created:** [August 25, 2018, 5:37am UTC](https://discuss.elastic.co/t/high-readthroughput-and-search-is-very-slow/145999 "2018-08-25T05:37:34Z")\
**Posts on this page:** 2\
**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 25, 2018, 5:37am UTC](https://discuss.elastic.co/t/high-readthroughput-and-search-is-very-slow/145999/1 "2018-08-25T05:37:34Z")

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I have 12 indices in one ES cluster (3 dedicated master nodes + 10 C4.4Xlarge data nodes). Each index has about 3.5 billions data and size is about 180GB. One index is allocated 8 primary shards + 1 replica. The node C4.4Xlarge has 32GB memory and 16 vcores, and I'm using AWS Provisioned EBS.

When I try to query one index with terms aggs, it takes 20 seconds to respond, and the ReadThroughput is very high. If I scale out the data nodes to 20, it only takes 1 seconds.

Is it normal under such configuration?

Does this mean that I need more memory so that more data can be cached in disk-cache? Or should I add more primary shards? Or ...

Any suggestions? Thanks!

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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 22, 2018, 5:46am UTC](https://discuss.elastic.co/t/high-readthroughput-and-search-is-very-slow/145999/2 "2018-09-22T05:46:27Z")

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