# Increased disk writes on elasticsearch

**URL:** <https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949>\
**Category:** Elasticsearch\
**Created:** [May 27, 2019, 5:28pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949 "2019-05-27T17:28:18Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![camjesus2](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@camjesus2](https://discuss.elastic.co/u/camjesus2)\
**Post date:** [May 27, 2019, 5:28pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/1 "2019-05-27T17:28:18Z")

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Hi all, kinda new to ES, so please bear with me.  
I've noticed a clear increse in disk WRITES more or less (but not quite) coincident with the upgrade to ES 7.  
I have only one node with around 150 shards ingesting data from logstash to filter and store server log information.  
Until a month ago, the disk write was "basically" zero. Then suddenly, around April 25th, it increased to around 5MB/s continuasly. Iotop shows java as the main responsible for this writes. CPU usage remains low as always.  
This in itself is not really a problem. The server can sustain the increased I/O, but I would really like to know what happened.  
What I did:

1. stopping elasticsearch, disk writes go down
2. stopping logstash, no changes
3. removing swap, no changes
4. increasing java heap, no changes
5. browsing the logs didn't show anything clear to me

Any clue on how to "troubleshoot" this would be appreciated. Browsing through the forum did show some similar issues but with clear causes that don't really apply to my case.

Thanks for any help you can provide,  
Best regards,  
Carlos

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**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:** [May 27, 2019, 7:10pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/2 "2019-05-27T19:10:21Z")

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It is possible that this is the issue fixed by [#42299](https://github.com/elastic/elasticsearch/pull/42299), so perhaps the simplest thing to do is upgrade to 7.1.1 when that becomes available, and see if this resolves your issue. If not then it'd make sense to dig further.

> [@camjesus2](#):
>
> Then suddenly, around April 25th, it increased to around 5MB/s continuasly.

How are you measuring this? How suddenly did the increase occur? How does this relate to your upgrade to 7.x in terms of timing?

> [@camjesus2](#):
>
> removing swap, no changes

We recommend [running without swap](https://www.elastic.co/guide/en/elasticsearch/reference/current/setup-configuration-memory.html) as a matter of course.

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**Author:** ![camjesus2](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@camjesus2](https://discuss.elastic.co/u/camjesus2)\
**Post date:** [May 27, 2019, 8:08pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/3 "2019-05-27T20:08:26Z")

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Hey DavidTurner, thanks for your reply.  
You seem to have hit something. As for your comments:

1. I visited #42299. Waaay too cryptic for me.

2. I'm monitoring all my servers using Netdata [([https://github.com/netdata/netdata](https://github.com/netdata/netdata))] and using elasticsearch for long term storage of data.  
The upgrade to 7.0.0 happened the 21st of April. After some unrelated glitches, on the 24th, the old 6.7 indexes where reindexed to 7.0. This is where things went awry. The reindexing took a few (around 4) hours where CPU and disk I/O spiked. After that , cpu went to it's normal values, but disk I/O never returned to baseline. See attached image; on the upper right graph, the green line is the server's disk writes.  
 ![image](https://us1.discourse-cdn.com/elastic/original/3X/e/5/e5653b8579d3ebbbba75fbf201a26348c72ebdec.png)  
All indexes (old and new) are green

3. Swap is a remnant from the past. I'll remove it eventually.

best regards!  
Carlos

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**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:** [May 27, 2019, 8:36pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/4 "2019-05-27T20:36:20Z")

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> [@camjesus2](#):
>
> the old 6.7 indexes where reindexed to 7.0. This is where things went awry.

Ok, that could well be consistent with the issue fixed by #42299. I wouldn't worry about the details, the key point is that this change should be included in 7.1.1, so let's wait for the upgrade before doing much more investigation.

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**Author:** ![camjesus2](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@camjesus2](https://discuss.elastic.co/u/camjesus2)\
**Post date:** [May 27, 2019, 9:03pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/5 "2019-05-27T21:03:11Z")

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Very well.  
Like I said, it's really not a critical issue for me. Just...anoying.  
Thanks again for your help. looking forward to 7.1.1 then  
Best regards,  
Carlos

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**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:** [May 28, 2019, 6:12pm UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/6 "2019-05-28T18:12:34Z")

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It looks like 7.1.1 is now available for download: [https://www.elastic.co/downloads/elasticsearch](https://www.elastic.co/downloads/elasticsearch)

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<div class="post-metadata">

**Author:** ![camjesus2](https://avatars.discourse-cdn.com/v4/letter/c/59ef9b/32.png) [@camjesus2](https://discuss.elastic.co/u/camjesus2)\
**Post date:** [May 29, 2019, 8:56am UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/7 "2019-05-29T08:56:51Z")

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Hi David,  
indeed it has and indeed it worked!  
Disk I/O went back to expected levels.  
Once again, thank you very much for your assistance.

Best regards,  
Carlos

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [June 26, 2019, 8:56am UTC](https://discuss.elastic.co/t/increased-disk-writes-on-elasticsearch/182949/8 "2019-06-26T08:56:55Z")

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