# Buffer

Previously defined in the [Buffering](https://docs.fluentbit.io/manual/1.9/concepts/buffering) concept section, the `buffer` phase in the pipeline aims to provide a unified and persistent mechanism to store your data, either using the primary in-memory model or using the filesystem based mode.

The `buffer` phase already contains the data in an immutable state, meaning, no other filter can be applied.

![](https://2011346993-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FpQx3Sex1V1mpQ54zINRe%2Fuploads%2Fgit-blob-ba80a23b4f579320e29e8e7faf0de64d0f74f894%2Flogging_pipeline_buffer%20\(1\)%20\(1\)%20\(2\)%20\(2\)%20\(2\)%20\(2\)%20\(2\)%20\(2\)%20\(2\)%20\(2\).png?alt=media\&token=a2f45cac-d928-44d5-8edf-33402897986b)

{% hint style="info" %}
Note that buffered data is not raw text, it's in Fluent Bit's internal binary representation.
{% endhint %}

Fluent Bit offers a buffering mechanism in the file system that acts as a *backup system* to avoid data loss in case of system failures.