Update on TFS and the upcoming Daylight Savings Time changes in the US
We continue to make progress testing TFS for the upcoming Daylight Savings Time changes. In an earlier post, I included details and links to information about the change and its affect on other Microsoft software. Our testing has uncovered the following 2 issues.
- If your server and client are not both running with DST OS patches, the date/times rendered by the web view vs. the client will differ. As long as the client uses the local machine timezone information and the server uses its local timezone information this can is the case today anyhow.
- The APIs/logic to compute DST built into Pre-Vista OS’s (and therefore the .NET TimeZone class that we use) does not support computing historical timezone information correctly. IOW, once someone has patched their machine to the new DST zones, times will not be computed correctly for date/times that occurred in a prior year during the window that differs with the current TZ data. What that means to us is that display values for changesets, WIT history, etc. will be wrong (by an hour) for certain dates that fall in those windows of time.
Neither of these issues are particularly serious as all of our dates are actually stored in UTC format. This means that generally only display is affected. From #1, I would generally recommend that you patch you server and clients at about the same time to reduce confusion. We are looking at #2. We will be switching to use the new .NET time zone class that enables accurate historical computation of local times. Exactly when we make that change is still to be determined but as the issue is pretty minor, we are not expecting to rush it.