I was a Vietnam Era Veteran with a 6-year obligation to the Air Force. I was in the IRR for two years after the end of 4 years of active duty. I now have no further connection or commitment.
I don't know where the 8 year figure comes form unless it's a new part of the law.
Once total obligation - including any reserve time - is served, enlisted personnel have no further obligation unless they are under the Standby or Retired Reserve, either by choice or status.
See:
http://www.defenselink.mil/ra/secondary/componentsfaq.h...