# Buffer

Previously defined in the [Buffering](https://docs.fluentbit.io/manual/1.6/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://3701111490-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LKKSx-3LBTCtaHbg0gl%2F-LKKTm4Y55lytnFhqfG1%2F-LKKTqrSt1OZi8vksZX_%2Flogging_pipeline_buffer.png?generation=1534737477823323\&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.