Thursday, February 26, 2009

Moving to Coordinated Universal Time (UTC)

by WindowsAzure via Windows Azure on 2/26/2009 5:17:00 AM

Currently, the time zone within Windows Azure is Pacific Standard Time (PST).  Soon, we’ll be migrating to Coordinated Universal Time (UTC).  This is potentially a breaking change for applications which rely on local time.

When will we make the change?

UPDATE [3/6/2009]: We'll be making this change starting Sunday, March 8th, at 10:00am GMT.  Thanks to all who gave us feedback on this plan.

We’d like to make this change soon, within the next few weeks.  Feedback from the community and the results of our internal testing will help us choose exactly when.  We'll post again to the blog and to the forum when the exact timing has been determined.

Why are we doing this?

Windows Azure is a global service.  To ensure that applications behave the same way regardless of their physical location, it’s important that Windows Azure have a consistent time zone across all geographies.  UTC is a natural choice given our global customer base, and UTC is not subject to Daylight Saving Time (and the associated risk of bugs).

What’s the potential impact to you?

If your application running in Windows Azure relies on local time, you will be impacted by the migration to UTC.  Here are a few examples of potential issues:

• Gaps may occur in event logs if local timestamps are used.
• User interfaces that depend on local timestamps may show different results.
• Local timestamps stored by your application may be interpreted differently after the changeover.

Many applications have already been designed to rely only on UTC time.  These applications should be unaffected.

Questions or concerns?

Please don’t hesitate to contact us on the Windows Azure blog or discuss this on the Windows Azure forum.