Uptime lying? Phantom reboot?

[peterneve]

I've just had a server which did something a bit strange. The monitoring software flagged it as down, but when I logged in, all of the proccesses were up still. The server didn't reboot, but the uptime utility shows about 30 minutes. There is an empty boot log and many linux processes have been restarted. Any ideas?

 

[mrregan]

Could anyone have changed it to single user mode, then
back to multiuser mode?

 

[peterneve]

Actually doing some more digging around this appears to be a Red Hat bug:

https://bugzilla.redhat.com/show_bug.cgi?id=97373

How reproducible:
ALWAYS

Steps to Reproduce:
1. Boot Linux system
2. Go away for 497 days
3. check uptime

Actual results:
[root@utility OLD]# uptime
15:59:01 up 23 days, 23:08, 6 users, load average: 0.10, 0.13, 0.09


Expected results:
[root@utility OLD]# uptime
15:59:01 up 520 days, 23:08, 6 users, load average: 0.10, 0.13, 0.09


This is a kernel problem. Uptime is basically jiffies, and at 100 Hz it wraps in
497 days

I guess a kernel upgrade is in order!

 

[Kozusnik]

Here's the calc for 32-bit Linux distros...

(2^32) / 8640000 (hundredths of a second in a day)

I've had mine flip multiple times. I haven't seen a 64-bit OS roll yet, I assume that by the same logic it would take...
2135039823350 days or 5849424173.55 years to roll

So I guess I'll have to wait and see.

Mark