If I recall correctly, NetApp suggests you don't cron rdate's to run on the hour because it's possible to step the clock past the hour and miss a scheduled event such as raid scrubbing or snapshots.
The don't provide NTP and then they discourage us from cron'ing rdate. What do they think?
I think the issue is when you run rdate. Just schedule rdate to run 37 minutes after the hour, or 12 minutes after the hour. If those involve a crossing of the hour boundary then you have other problems.
-Michael Cerda