Time jumps backwards on reboot

[jim1944]

Just installed F15 using preupgrade (from F14) and now, every time I reboot, time jumps backwards 4 hours. If I reboot twice in a row without correcting the time, time will be off by 8 hours. Time zone is set correctly (Eastern Time). "Synchronize date and time over the network" is unchecked.

Since the difference between GMT and Eastern time is 4 hours, there appears to be some confusion over that but I can't find anything in the "Date & Time" app relative to that to try to play with to see if I can correct this. II do remember a similar issue many releases ago but I can't remember how it was dealt with.

Any ideas on how to diagnose and fix this?

Thanks
Jim

[smr54]

First check time in the BIOS. Though upon shutdown, usually the system will adjust the hardware clock. If, for example, you have Fedora and Windows, with Windows using local time and Fedora using GMT, this can cause problems when you boot from one to the other.

The place I use to check is /etc/adjtime. In there it should say either LOCAL or UTC.

[jim1944]

/etc/adjtime has third line set to LOCAL and that is what the BIOS clock is set to and needs to be set to because I'm dual booting with Windows.

This is the issue I could not remember: http://forums.fedoraforum.org/showthread.php?t=190556. It is exactly the same symptoms I am having now. But that was with an older machine that has since been replaced with a Dell (AMD Athlon(tm) II X2 240 Processor × 2 with 3.6 G of memory).

I did not have this problem with either F13 or F14, so it is "new" except that it matches this F9 bug: https://bugzilla.redhat.com/show_bug.cgi?id=447019, which was not fixed.

I suppose I could solve this the same way I did it in F9. However, the old machine had Windows 98 on it and I never used it so confusing Windows was not a real issue; my current machine has Windows 7 and I do use it so I'd like a solution that did not confuse Windows.

Just to make sure nobody gets confused about what the problem is: this has nothing to do with alternating between Windows and F15

Thanks
Jim

[Miikka]

I remember seeing a thread here recently where someone was experiencing the same problem as you. Only he experienced time jumping forwards. Try searching these forums if that thread ever got a solution.

[jpollard]

Check your BIOS battery. This has been known as a symptom of a weak/dying battery loosing time.

One test you can do is look at the clock from the BIOS, then reboot/power cycle and look again (from the BIOS). If the clock drops time then, it will have to be the battery or a bad motherboard (most likely battery).

If you can live with a dead battery and have a network connection at boot, you can use the ntpdate procedure (chkconfig ntpdate on) and it will set the date based on an internet time server (defined in /etc/ntp.conf)

[briand]

I agree with jpollard, but with a 'buyer beware' clause: the ntpd (or ntpdate) daemons also try to update the hardware clock, and you'll get errors (probably in /var/log/messages) if the time cannot be written to the hardware clock... I had this issue on one of my machines, recently. In my case, replacing the CMOS battery cured the problem with the hardware clock.

[jim1944]

I guarantee you this has nothing to do with the BIOS battery or a bad motherboard. It is a bug in Fedora 15.

On each reboot of F15, time jumps backwards 4 hours. Time is consistent on reboots of Windows 7. If I check the "System clock uses UTC" box in the Data/Time app, time is displayed as 4 hours less than the BIOS clock but that does not change on reboot. A bad battery or bad motherboard would not get you that kind of behavior - it would be more erratic.

So, for now, I've checked that box but set the BIOS clock to local time. When I run Windows 7 I see correct time, when I run F15 I see time 4 hours off. But at least it is not jumping backwards on each reboot.

My theory: there are two places where Fedora stores whether the BIOS clock is UTC or LOCAL. On boot up it looks at one to decide whether to adjust what it gets from the BIOS clock for use as system time. At shut down it looks at the other to determine if the BIOS clock needs to be "corrected". One of those places is /etc/adjtime. This is the one it uses at shut down and is the one updated by checking/unchecking the "System clock uses UTC" box. I have no idea what the other one is but it is the one used at boot up. Here's what I think happens with "System clock uses UTC" box in the Data/Time app NOT checked :
1. at boot up, system checks the other source and sees (incorrectly) that BIOS clock is UTC and subtracts 4 hours for display in the clock.
2. at shut down, system checks /etc/adjtime and sees that BIOS clock is local and notes the 4 hour difference between what it thinks local time is and what the BIOS clock has and so decides to correct the BIOS clock.

Jim

[briand]

Originally Posted by jim1944

I guarantee you this has nothing to do with the BIOS battery or a bad motherboard. It is a bug in Fedora 15.

well, since you guarantee it... we should assume that you've already filed a bug report via Bugzilla, and this thread is just an idle exercise for you to pass the time while you wait for the developers to finish diagnosing and fixing the bug that you found?

[jim1944]

Bug 709924. If I'm wrong your money will be cheerfully refunded, per the money back guarantee.

Jim