# Rule Filesystem in percentage

**URL:** <https://discuss.elastic.co/t/rule-filesystem-in-percentage/291228>\
**Category:** Elastic Observability\
**Tags:** elastic-stack-alerting\
**Created:** [December 8, 2021, 2:16pm UTC](https://discuss.elastic.co/t/rule-filesystem-in-percentage/291228 "2021-12-08T14:16:36Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![fernandofot](https://avatars.discourse-cdn.com/v4/letter/f/dbc845/32.png) [@fernandofot](https://discuss.elastic.co/u/fernandofot)\
**Post date:** [December 8, 2021, 2:16pm UTC](https://discuss.elastic.co/t/rule-filesystem-in-percentage/291228/1 "2021-12-08T14:16:36Z")

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Hi Guys,

I would like to know which metrics of the filesystem are you using to create an alert to send by email, the detail here is I would like to send an alert when the disk C: or /opt/ hit 90%, for example.

I installed the metricbeat on the server. The metrics are showing. I installed the system module.

I found the metric: system.filesystem.used.bytes, however, the metric do not allow to the creation of an alert by percentage.

![filesystem_rule](https://us1.discourse-cdn.com/elastic/original/3X/d/3/d37c36785cbb3e20f434275bda7dbb3e9b3b5124.jpeg)

Could someone help me in this case?

Kind Regards,  
Fernando

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**Author:** ![fernandofot](https://avatars.discourse-cdn.com/v4/letter/f/dbc845/32.png) [@fernandofot](https://discuss.elastic.co/u/fernandofot)\
**Post date:** [December 9, 2021, 8:25pm UTC](https://discuss.elastic.co/t/rule-filesystem-in-percentage/291228/2 "2021-12-09T20:25:45Z")

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I found out the metric: system.filesystem.used.pct

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**Author:** ![weltenwort](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/weltenwort/32/53885_2.png) [@weltenwort](https://discuss.elastic.co/u/weltenwort)\
**Post date:** [December 13, 2021, 1:10pm UTC](https://discuss.elastic.co/t/rule-filesystem-in-percentage/291228/3 "2021-12-13T13:10:17Z")

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Thanks for sharing your solution!

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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:** [November 4, 2022, 8:33am UTC](https://discuss.elastic.co/t/rule-filesystem-in-percentage/291228/4 "2022-11-04T08:33:17Z")

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