Steve ... Linux/390 will synch time with NTP just as effectively as Linux on a PC will. VM does not benefit from this (but is not harmed by it). I have *not* found NTP to be a resource hog; in fact, it is designed to be kind of low impact. (Seems to sleep a lot waiting for time to pass and then check again what time it is.)
Hopefully you have an internal time reference. If not, you'll have to find one outside of your network. (Probably okay, but there's no telling how responsive they will be since it is a courtesy of sorts.) You're welcome to hit my personal network (at home). Contact me off list for that addr. (I'm not in the NTP biz.) -- R;
