Constant MAX_SECTION 

pub const MAX_SECTION: usize = _; // 8_388_608usize

The most bytes of records a shard hands to its log at a time (one record at least, however long). A shard that fell behind (a stalled flush, a burst of starts) then writes its backlog as sections of this size, so no batch, replicated entry or protocol frame built from sections grows with the backlog; a flush that keeps up never comes near it.