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VM Can't Boot After Increasing Disk Size

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Hello All,

I ran into a bit of a problem. I had a machine with 64GB disk space available, on which Windows 10 Pro was running. 64GB However proved to be slightly too short of what I required it to be. While the machine was running, I increased the disk size in ESXI (Edit -> Hard Disk 1 -> from 64 to 480). In windows I created a new volume of around 400GB with the new space that was available, and everything was just nice and as expected. Until I rebooted.

"An operating system wasn't found. Try disconnecting any drives that don't contain an operating system."

Now, I haven't changed anything other than increasing the disk size and adding a new volume. Why can't it find the operating system anymore? I went into the bios and checked if it somehow tried to boot off the other volume, but I can't even find it there; just "Hard Drive" with VMware Virtual SCSI Hard Drive and Bootable Add-in Cards "in" it. I have no idea how to resolve this issue, but I really can't miss this VM.

Any help or advice would be highly appreciated:)

Kind regards,

Remy

----------------------- Edit --------------------------

I have booted from the installation CD and removed the extra volume I've created. No success.

Tried to do a Start-up Repair, Uninstall Updates, System Restore, nothing works. They all just fail.

Diskpart at least still sees the 64gb volume as the C drive, so that's something.

----------------------- Edit 2--------------------------

I tried to rebuild the BCD, resulting in something rather unexpected. It successfully found a Windows installation, but when I tell it to add the installation to the boot list, it prompts me with "The requested system device cannot be found.", even though it just found it. urgh.

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----------------------- Edit 3--------------------------

The hard disk is listed as SCSI, listing it as SATA or IDE doesn't work either.

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After rebuilding de BCD, apparently it was found as an actual OS again. From there on I could fix startup issues in the troubleshoot section of "Repair my pc", which resolved the issue entirely. I still have no idea why this happened, but if anyone ever for some reason runs into this issue:

- Make sure that the main boot disk is on top in the boot priority tab

- Boot from the CD

- Go to "Repair my PC"

- Open the terminal in troubleshoot

- Run these commands:

     - bootrec /FixMbr

     - bootrec /ScanOs

     - bootrec /RebuildBcd

- Restart the VM and go to "Repair my PC" once again

- "Fix Start-Up" should now work, and after that, the VM should boot again.

Thanks continuum​ for the suggestions, they got me further:)

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>> I went into the bios and checked if it somehow tried to boot off the other volume, but I can't even find it there;

>> just "Hard Drive" with VMware Virtual SCSI Hard Drive and Bootable Add-in Cards "in" it.

What are you surprised about ???

In the first tabs of the virtual BIOS only IDE-disks will be listed.

SCSI-disks are only mentioned in the tab where you configure the bootorder.
So this is expected behaviour.

Possible reasons for "not booting after increase vmdk" actions are:

- missing boot-flag with MBR-disk

- corrupt GPT-table

- misconfigured boot-order in virtual BIOS or EFI-firmware

For first 2 reasons you would boot into a LiveCD with gParted and repair it.

To fix bootorder for SCSI-vmdks go into

>> >> just "Hard Drive" with VMware Virtual SCSI Hard Drive and Bootable Add-in Cards "in" it.

and make sure that your boot.vmdk is on top of the list.

Do you need support with a recovery problem ? - call me via skype "sanbarrow"
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Thank you for your reply.

I've been trying to fix the MBR and rebuild the BCD, the BCD part worked out in the end and when I go into troubleshoot from the installation medium it also contains the option "Continue > Exit and continue to Windows 10 Pro N". When I click on this it still dies though, still no bootable disk found. Does this mean that it is in fact the MBR that's somehow dead?

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After rebuilding de BCD, apparently it was found as an actual OS again. From there on I could fix startup issues in the troubleshoot section of "Repair my pc", which resolved the issue entirely. I still have no idea why this happened, but if anyone ever for some reason runs into this issue:

- Make sure that the main boot disk is on top in the boot priority tab

- Boot from the CD

- Go to "Repair my PC"

- Open the terminal in troubleshoot

- Run these commands:

     - bootrec /FixMbr

     - bootrec /ScanOs

     - bootrec /RebuildBcd

- Restart the VM and go to "Repair my PC" once again

- "Fix Start-Up" should now work, and after that, the VM should boot again.

Thanks continuum​ for the suggestions, they got me further:)

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