Daylight savings and timezones

A customer has a system that needs to record a log of events on the production line. Each event needs to be timestamped, and the timestamps need to be monotonically increasing. That is, we'll be doing calculations on the length of processes by subtracting timestamps.

The difficulty is that this is a system that will be up 24x7, and will be running during the daylight saving stime conversions.

My initial approach would be to keep times in GMT, but looking at Oracle's date support, I'm not sure how I would do it. SYSDATE seems to return local time, and I don't see an easy way to find out what Oracle thinks the current time zone is.

Be that as it may, this can't be an uncommon problem, how do people usually deal with it?

-- 
Of all tyrannies, a tyranny exercised for the good of its victims may be the
most oppressive. It may be better to live under robber barons than under
omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep,
his cupidity may at some point be satiated; but those who torment us for our
own good will torment us without end, for they do so with the approval of
their consciences. 
                                - C. S. Lewis