The syssegments table, one in each database, lists the segments in a database. A segment is a collection of the database devices and/or fragments available to a particular database. Tables and indexes can be assigned to a particular segment, and therefore to a particular physical device, or can span a set of physical devices.
create database makes default entries in syssegments. The system procedures sp_addsegment and sp_dropsegment add and remove entries from syssegments.
