Yesterday, I was working into my vsphere Lab where I have deployed one virtual machine into the environment. After deployment virtual machine was working perfectly fine. After some time, I have added 2 huge hdd of size 800 GB using PVSCSI. Once I added the hdd into the VM, and after accepting the change, I tried to open the console and found vm has rebooted and stuck at "Operating System not found" That’s look wired, as I have just added the hdd online and suddenly it rebooted and stuck at this stage. To troubleshoot this issue I tried to gracefully shutdown the VM and tried to bring online in hope, it will detect the changes, but again it stuck at same level "Operating System not found" I checked my OS drive which is  created with the LSI SCSI controller, and the 2 new hdd I created with PVSCSI controller. Here is what the problem exists!!!!! Basically, When the virtual machine is created with the LSI SCSI controller,