Server not booting - Operating System not found on start up screen
 

Hello Linux/VMWare community,

I am facing issues after rebooting one of my RedHat Linux7 server in VMWare VSphere 7 environment.

Server is not booting up after rebooting the server. It is unable to boot from disk. It says Operating System not found.. it is unable to find the disk to boot from ..

The VM is a backup VM which is used to take backups of other VMs and also used to restore the VMs from backup. I see that there are multiple disks of different VMs (that were being backed up) attached to this VM. Some of them are still attached to this VM. Some of the virtual hard disks are of bus type SATA while others are SCSI bus type. And the server was rebooted after verifying no active backup job being run on the VM. After reboot, server is not booting up..

I checked the VM options, went into BIOS and selected Hard disk to be at the top of the boot order and tried to check the hard disk sequence to boot from.. But I am unable to find SCSI0:0 disk in the list of hard disks inside BIOS that holds my Operating system. On the screen to change boot priority, I can just see hard disks with bustype SATA maximizing the Hard disk options. I am unable to see any disks with bus type SCSI in that menu.. so I am unable to force the VM to boot from specific hard disk that has my OS. or atleast put my hard disk which has OS to be at the top in Hard disk priority.

Do you have any suggestions? Any suggestions would be highlights appreciated.

Two things come to my mind:

1. The SCSI controller. If this VM has recently been updated, does it have support for the correct SCSI controller? The LSI Logic SAS is the "safe" one to choose in VMware, and it should work with most distros. You can switch it back to PV-SCSI after you're sure that the driver is loaded.

2. EFI support. RHEL 7 should *I think* have support for EFI, but perhaps it wasn't switched on at the time you ran the installation. Subsequently switching it on will cause the error you're seeing. And vice versa: If it was on at installation, subsequently switching it off will also cause this type of error.

Failing either of those two, you could try booting the VM with a live CD iso, and poke around to see what's wrong... eg: why it isn't finding the disk, which controller it expects, etc.

It's been suggested to you for quite some time now to actually pay for support for the commercial products you're using, such as Oracle, RAC, RHEL, and VSphere. When you do so, you can get assistance easily.

Beyond that, rkelsen gave some good advice. But you again aren't giving us any details, like what kind of server this is, with what hardware/disks, etc. Too many variables to guess at. If you have ONE VM server that's working on that box, that rules out a lot...which leaves you that one disk. Since we don't know what type of disk it is past SCSI, or how it's connected, can't offer more advice other than "check that disk".