View Full Version : [ubuntu] V10.10, time issue when going back to Windows OS

March 27th, 2011, 07:46 PM
Hi all,

New here and new to Ubuntu. I'm looking forward to reading and learning from you guys! I have a problem I can't seem to figure out.

When I boot the Ubuntu hard drive the clock and date are correct, then when I restart and go to my Windows hard drive, my Windows time is always 5 hours incorrect. When I first boot Windows my clock is correct(after I reset it) this only happens after I have rebooted from an Ubuntu session and just restarted the box to go to Windows. Any ideas?


March 28th, 2011, 03:04 AM
A buddy helped me find this and it does work. I did the Linux mod.

Multiple Boot Systems Time Conflicts

Operating systems store and retrieve the time in the hardware clock located on your motherboard so that it can keep track of the time even when the system does not have power. Most operating systems (Linux/Unix/Mac) store the time on the hardware clock as UTC (http://en.wikipedia.org/wiki/Coordinated_Universal_Time) by default, though some systems (notably Microsoft Windows) store the time on the hardware clock as the 'local' time. This causes problems in a dual boot system if both systems view the hardware clock differently.
The advantage of having the hardware clock as UTC is that you don't need to change the hardware clock when moving between timezones or when Daylight Savings Time (DST) begins or ends as UTC does not have DST or timezone offsets.
Changing Linux to use local time is easier and more reliable than changing Windows to use UTC, so dual-boot Linux/Windows systems tend to use local time.
Since Intrepid (8.10), UTC=yes is default.

Make Windows use UTC

Note: This method was not initially supported on Windows Vista and Server 2008, but came back with Vista SP2, Windows 7 and Server 2008 R2.
To make MS Windows calculate the time from the hardware clock as UTC.

Create a file named WindowsTimeFixUTC.reg (https://help.ubuntu.com/community/UbuntuTime?action=AttachFile&do=view&target=WindowsTimeFixUTC.reg) with the following contents and then double click on it to merge the contents with the registry:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\TimeZoneInformation]
Make Linux use 'Local' time

To tell your Ubuntu system that the hardware clock is set to 'local' time:

edit /etc/default/rcS
add or change the following section # Set UTC=yes if your hardware clock is set to UTC (GMT)