mjhjmtu

I have cron command that runs a shutdown bash script at 12:10am every day.

10 0 * * * /bin/bash /var/www/scripts/special-reboot.sh

The script is very basic, all it does is shutdown nginx and moves data from MEMORY tables in MySQL to normal tables. Then it performs sudo /sbin/shutdown -r now 'Daily restart.'

It's been running well for about a month or two, however last night something very strange happened and I need to know why.

I have a python logging script which checks that important processes are running every 15 minutes. After the reboot last night, the log looked like this (note the dates and times).

[2019-02-12 23:45] 
...
[2019-02-13 00:00]
...
[2016-11-04 03:30]
...
[2016-11-04 03:45]
...
[2016-11-04 04:00]
...
[2016-11-04 04:15]
...
[2016-11-04 04:30]
...
[2016-11-04 04:45]
...
[2016-11-04 05:00]
...
[2016-11-04 05:15]
...
[2016-11-04 05:30]
...
[2019-02-13 02:30]
...
[2019-02-13 02:45]
...
[2019-02-13 03:00]

As you can see, it suddenly starts counting from a different date time for about two hours, and then it goes back to normal.

The scariest part is that it wasn't only the python script that was affected. Another C script that tracks electrical pulses is missing data from that period of time.

I don't know what could've caused this. I know, due to my logging script that all of the important programs were running absolutely fine during this time period. I believe this is most likely a problem with the system rather than my programs.

There is no real time clock (RTC) on the raspberry pi.

The Raspberry Pi is designed to be an ultra-low cost computer, so a lot of things we are used to on a computer have been left out. For example, your laptop and computer have a little coin-battery-powered 'Real Time Clock'  (RTC) module, which keeps time even when the power is off, or the battery removed. To keep costs low and the size small, an RTC is not included with the Raspberry Pi. Instead, the Pi is intended to be connected to the Internet via Ethernet or WiFi, updating the time automatically from the global ntp (nework time protocol) servers

You can buy one for the raspberry pi for about $6 USD. Otherwise NTP is your only option.