Requirement for deep molecular rarefaction inside low aperture beam pipe in presence of high intensity Synchrotron Radiation together with very tight magneto-optical system makes performance of vacuum system for modern high brightness Synchrotron Radiation Sources (SRS) quite challenging. To avoid emittance blow-up its beam pipe must be as smooth as possible along beam propagation. It relates to all components like flange connections, pumping ports and compensators also. In addition, the vacuum system must be stable over years against inevitable micro-leaks and suitable for possible modifications of other systems, which require its air venting. The paper presents a conception of the SRS SKIF vacuum system fitting the set of requirements. A simplified model for estimation and optimization of a scenario for the vacuum system conditioning is also described.