Why the filesystems' available space displayed in RFC2790 are 5% greater than the values displayed in Unix/Linux "df" command?

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Article ID: 37615

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CA Spectrum

Issue/Introduction



Why the filesystems' available space displayed in RFC2790 are 5% greater than the values displayed in Unix/Linux "df" command?


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Environment

Release:
Component: SPCDIS

Resolution

By default, the Unix/Linux filesystems have some space (5%) reserved for the super user (root). This means that no regular users can fill the filesystems up to 100%, and so it's always going to have enough free space to continue its normal function.

This difference appears because this information is not included in RFC2790 data.

You have 3 options to workaround this behavior:

1- Set the reserved space of the referred filesystems to 0% using the "tune2fs" command. Please refer to the documentation of the Operational System in use to get the instructions on how to configure it.

Note: You must consider the risk of this configuration, since this is a feature that protects the filesystem to be filled up by regular users.


2- If  CA SystemEDGE agent is installed on the machine, and it is modeled in Spectrum as a SystemEDGE host, select the Unix/Linux server and go to "Component Detail” -> “Information” tab -> "File Systems" -> "File Systems" and monitor the disk from there:

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Note: The small difference of results between "df -h" command and the above screenshot occurs because the values displayed by "df" command are rounded.


3- If the options above are not applicable, you must consider the difference of 5% when monitoring disks using RFC2790.

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