# Estimate disk write or read when merge processing

**URL:** <https://discuss.elastic.co/t/estimate-disk-write-or-read-when-merge-processing/62342>\
**Category:** Elasticsearch\
**Created:** [October 6, 2016, 7:18am UTC](https://discuss.elastic.co/t/estimate-disk-write-or-read-when-merge-processing/62342 "2016-10-06T07:18:06Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![itplayer](https://avatars.discourse-cdn.com/v4/letter/i/d26b3c/32.png) [@itplayer](https://discuss.elastic.co/u/itplayer)\
**Post date:** [October 6, 2016, 7:18am UTC](https://discuss.elastic.co/t/estimate-disk-write-or-read-when-merge-processing/62342/1 "2016-10-06T07:18:06Z")

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Hi,  
I monitor my ES cluster merge process through http api /\_nodes/stats/indices every 1 min and record the diff between.

Here is my sampled data:

Given 2 data collected  
18:00 --\> total\_size\_in\_bytes: 145600300; total\_time\_in\_millis: 23000  
18:01 --\> total\_size\_in\_bytes: 195000000; total\_time\_in\_millis: 25000

1. Can I say about 50 MB merged and cost 2 sec  
If the answer is yes, 50MB is estimated "write 50MB" to disk as final merged segment file or read 50MB from other segment files those are being merged? If this is "disk write", the performance is 25MB/per sec? Can I throttle this behavior?

Your help is highly appreciated. Thank.

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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:** [July 5, 2017, 10:14pm UTC](https://discuss.elastic.co/t/estimate-disk-write-or-read-when-merge-processing/62342/2 "2017-07-05T22:14:27Z")

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Closed on July 5, 2017, 10:14pm UTC