1) Check if vsh is running via "vsh status". If all service is failed to start check if any error message on console.

2) If services have restarted without core dump them one should look at /var/log/monit.log Monit in the only one which can restart services.

3) Monit would do it if a process-id (PID) it. is tracking (that of infmgr, vsmd, confd) is no longer there. So if one of these processes does graceful exit, then monit will detect that the process is no longer running and will restart services. 

4) Now next question will be why did that process exit if there was no core.  . If the system is running on memory, then Ubuntu will kill the process that is consuming large amount of memory.

5) Check if vmsd consuming large memory, if yes, vsmd is killed , there won't be any cores. to confirm this check versa-service.log, it will be look like “killed” somewhere near the “versa-service poststop” line.

admin@CPE1-vcsn-a1:~$ ps aux | grep infmgr

versa 11065 0.0 0.2 69808 18508 ? S Nov26 0:07 /opt/versa/bin/versa-infmgr -N

admin@CPE1-vcsn-a1:~$ sudo kill -9 11065

admin@CPE1-vcsn-a1:~$ sudo tail -f /var/log/monit.log

[PST Nov 26 13:24:00] info : 'CPE1-vcsn-a1' monitor action done

[PST Nov 29 07:08:34] info : Shutting down Monit HTTP server

[PST Nov 29 07:08:34] info : Monit HTTP server stopped

[PST Nov 29 07:08:34] info : Monit daemon with pid [11327] stopped

[PST Nov 29 07:08:34] info : 'CPE1-vcsn-a1' Monit 5.17.1 stopped

[PST Nov 29 07:08:37] info : Starting Monit 5.17.1 daemon with http interface at [localhost]:2812

[PST Nov 29 07:08:37] info : Monit start delay set -- pause for 30s

[PST Nov 29 07:09:07] info : Starting Monit HTTP server at [localhost]:2812

[PST Nov 29 07:09:07] info : Monit HTTP server started

[PST Nov 29 07:09:07] info : 'CPE1-vcsn-a1' Monit 5.17.1 started

>>>>>>> See the below log once I kill infmgr <<<<<<<

[PST Nov 29 13:29:45] error : 'versa-infmgr' process is not running

[PST Nov 29 13:29:45] info : 'versa-infmgr' trying to restart

[PST Nov 29 13:29:45] info : 'versa-infmgr' start: /opt/versa/scripts/async_restart.sh

[PST Nov 29 13:29:46] error : 'versa-infmgr' failed to start (exit status 0) -- /opt/versa/scripts/async_restart.sh: warning: commands will be executed using /bin/sh

job 335 at Thu Nov 29 13:29:00 2018

[PST Nov 29 13:29:46] info : Shutting down Monit HTTP server

[PST Nov 29 13:29:46] info : Monit HTTP server stopped

[PST Nov 29 13:29:46] info : Monit daemon with pid [16865] stopped

6) The most common reason to restart the service is high memory usage.

7) Try to fix the grub via vsh fixgrub. Once it run this command it will display the if grub is successfully recovered or not. If no message displayed then it command is not able to fix grub.

8) If all services failed to start , then run "sudo update-grub". This forced the Linux to setup grub correctly. They were/are running an older version of software. The issue was that package installation was aborted because it appears they rebooted the box in the middle. So had to redo the installation.

9) If device is physical and not coming up, then try to boot via external device such CD/USB. 

10) During start of boot if error "Invalid video mode specification 'text'. Booting in blind mode" then try to re-burn in Non-UEFI mode , Change the setting in bios to boot in non-UEFI mode.