How does the cdm probe detect and alarm on computer reboot?
Here is how the cdm information is found and alerted on:
CDM probe does not care if the server was gracefully restarted or if the server did a reboot due to a crash. As far as CDM knows, it is a reboot.
Below are the commands that are used:
- On Unix--> /proc/uptime
- On Windows--> We determine the uptime from the 'System' performance monitor (perfmon) and calculate the boot time from there.
Perfmon Counter->System-> "System Up Time"
System Up Time is the elapsed time (in seconds) that the computer has been running since it was last started. This counter displays the difference between the start time and the current time.
There is a file in the cdm folder which contains the uptime value. If the value obtained is different from the value in the file then an alarm is sent.
the file name is cdm.data and has a structure as follows:
boot_time = 1550241585
When CDM starts up, it checks what it has recorded for boot_time, and also checks the current uptime. If all of a sudden the uptime is a smaller number than boot_time, meaning the uptime is 'less than it was before', a reboot has occurred and an alarm is sent.
When you use Infrastructure Manager and choose Raw configure you can view the cdm.cfg entry from there as well.