2 minute jumps are WAY
too big -- they may do weird things to your file date consistency. I would work in tenths or 1/100's of a second & I would do some research on the 'Net before I decided what size each increment should be. "NTP" is a good Google starting point.
First, I would be sure that the problem is real. Not to be rude or insulting, but how do you know you have a problem? And how did it get so big? What are the symptoms? Could they be masking a different problem?
Consider the following:
- Exactly 1 hour?
- Do you know how this happened?
- Is this in any way related to daylight time?
- Is this in any way related to a time zone error?
- Is your hardware (BIOS) clock set to UTC or local?
- How do you normally keep this server synced?
- What do you sync to?
- Do you serve time to your LAN?
- Is there no automatic & more gradual method provided?