# Sizing Elasticsearch
**URL:** https://discuss.elastic.co/t/sizing-elasticsearch/203134
**Category:** Elasticsearch
**Created:** [October 11, 2019, 3:01am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134 "2019-10-11T03:01:16Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@yeziblo](https://discuss.elastic.co/u/yeziblo)
#### Post date: [October 11, 2019, 3:01am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134/1 "2019-10-11T03:01:16Z")
Hi everyone,
I want to plan the ES cluster reasonably:
1. I have 15 nodes and each nodes have 125G RAM and 31 CPU;
2. The total size of data is 30T(include replica);
3. The total count of shards is 7100(include replica);
4. Es version is 6.8.0;
5. index and search are all frequently;
How do I size my cluster? (how many master node do i need? Whether several coordinate nodes are required)
Best Regards!
---
### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [October 11, 2019, 5:39am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134/2 "2019-10-11T05:39:34Z")
> [@yeziblo](#):
>
> How do I size my cluster
It sounds like you have already sized your cluster and have it up and running. How is it performing?
> [@yeziblo](#):
>
> how many master node do i need?
You generally should have at least 3 master-eligible nodes, but 3 is often the optimal number. If your cluster is deployed across a larger number of availability zones/racks you may increase this.
> [@yeziblo](#):
>
> Whether several coordinate nodes are required
This depends a lot on the use case, as coordinating-only nodes are often not required. If you have a lot of querying you can add this type of node to see if it improves performance. Set the number so they are under reasonable load.
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### Author:  [@yeziblo](https://discuss.elastic.co/u/yeziblo)
#### Post date: [October 11, 2019, 5:59am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134/4 "2019-10-11T05:59:19Z")
@Christian_Dahlqvist Yes, the cluster had been running for some time before I took over，and because the cluster's configuration is default value, query efficiency is not ideal.
I want to optimize the cluster by resizeing the cluster.
But I found that although I knew some theory, I still didn't know how to start in practice…
for example:
Does 125G ram is too big to a node(es node's jvm can not cross 32G)? is it better to deploy multiple es instances on one node?
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [October 11, 2019, 6:38am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134/5 "2019-10-11T06:38:07Z")
Your setup looks reasonable. Have you identified what is limiting performance? Is it CPU? Disk I/O and utilisation? Heap pressure and GC?
What does the workload look like?
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### Author:  [@yeziblo](https://discuss.elastic.co/u/yeziblo)
#### Post date: [October 11, 2019, 6:49am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134/6 "2019-10-11T06:49:38Z")
Hi, @Christian_Dahlqvist
the workload now looks good:
but sometimes the query efficiency is not good.
Do I need to set up extra ES instances on each node? I think 125GB is too much big.
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [November 8, 2019, 6:49am UTC](https://discuss.elastic.co/t/sizing-elasticsearch/203134/7 "2019-11-08T06:49:44Z")
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