There is a rather annoying bug in the sysinfo C library if you’re running the OpenVZ kernel version 2.6.32 or higher. The problem is that the library used to return correct values for the uptime report, but since a few months appears to be broken and always returns 0. If you’re using monitoring agents (ie: zabbix) that rely on that sysinfo() call to determine the uptime, you’ll get funky reports about servers keeping their uptime of 0 minutes.
Here’s a way to verify the problem. Create a small C-program like this, called stats.c.
#include <sys/sysinfo.h>
#include <stdio.h>
int main() {
struct sysinfo sys;
/* Get the sysinfo */
sysinfo(&sys);
/* Output */
printf("Uptime in seconds: %d\n", sys.uptime);
return 0;
}
Compile it and run it.
~# gcc stats.c -o stats ~# chmod +x stats ~# ./stats Uptime in seconds: 0 ~# uptime 16:44:27 up 27 min, 0 users, load average: 0.00, 0.00, 0.00 ~# cat /proc/uptime 1685.92 151770.28
And it will always output “Uptime in seconds: 0", regardless of your actual uptime reported in /proc/uptime or via the uptime command.
If you’re having this problem with Zabbix Agents, there’s a bugreport filed as ZBX-4230 but since it’s an actual problem only on OpenVZ, I think we can only hope to see it fixed in Bug 2051 at OpenVZ.org.