You can write trace data to a file continuously as an extension to the in-storage trace, but instead of one buffer per thread, at least two buffers per thread are allocated.
A ring buffer is a logging technique for applications whereby the relevant data to be logged is kept in memory instead of writing it to a file on a disk every time.
Most of the file systems communicate through a buffer cache, which is a cache that optimizes access to the physical devices by caching recently touched data.