Constant SEGMENT_BYTES 

const SEGMENT_BYTES: u64 = _; // 67_108_864u64

Roll to a new segment past this size. Segments are the unit of deletion, so this trades how much dead log is retained past its watermark against how many files the directory holds. At section 11’s measured 190.6 MiB/s a segment is about a third of a second of ingest.