# Buffer

Previously defined in the [Buffering](https://docs.fluentbit.io/manual/1.7/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://4045743255-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LKKSx-3LBTCtaHbg0gl%2Fsync%2Fba80a23b4f579320e29e8e7faf0de64d0f74f894.png?generation=1619826203383819\&alt=media)

{% 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.