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How to recover bootloadera ?


I have a dual-boot setup: Windows 10 + Ubuntu 20.04. I have 2 SSDs (both are Samsumg 860 EVO 1TB, in case it matters), but since I bought them at different times I made my partitions a bit weird:

SSD-1: (i believe there were also 2 or 3 tiny system reserved partitions, like Windows Recovery and EFI partition)

(NTFS) Windows 10 C: partition (~260GB)
(NTFS) Data partition (~670GB)

(NTFS) Data partition (~850GB)
(ext4) Linux root partition (~20GB)
(ext4) Linux home partition (~55GB)
One day, I was using Ubuntu and I shut down my PC. Later that day, I booted just to be met with the UEFI BIOS setup screen, because it couldn't find any boot devices.

At first, I thought that I messed something up with the bootloaders so I inserted a Windows 10 installation disk and went into recovery mode. The built-in recovery tool proved to be useless (as it always does), so I started Command Prompt and found that drive C: is my SSD-2 data partition. It couldn't find the first SSD!

I decided to boot into a Linux live session, since it has more tools available. GParted showed me that /dev/sdb only had the NTFS partition (the 75GB of ext4 were unallocated space), while /dev/sda was corrupted entirely: about 40MB of unallocated space at the beginning and the rest of it was a single partition with an unknown filesystem.

I took SSD-1 out to another Windows computer and the Disk Management tool shows the same thing. I should mention it was a GPT disk, but I don't know if that helps (usually, if a PC cannot read GPT disks it reports it as a single unknown partition, but my PC is very much GPT-aware).

So my question is: What can I do? Can I recover my 2 SSDs? (especially that data partition)

UPDATE: I used AOMEI Partition Assistant to recover all partitions. Now I am able to boot into Linux, however Windows still gives me some weird error on a blue screen (it's not a BSoD, it doesn't have the sad face): A required device isn't connected or can't be accesed.


  • coop
    coop Posts: 915

    Dual Boot used to be safer; I have found that with EFI the likelihood of adventures such as you have described has increased. In particular, updates of either Windows or Ubuntu (or Fedora/Red Hat/CentOS etc) like to pretend the other OS does not exist on occasion, and in particular they overwrite the boot loader configuration occasionally, alhtough without data destruction on data partitions. If you are running Linux, the program called "efibootmgr" lets you control which OS you boot into, whether it is on one disk or two. Most of my experience is with one disk, I have not had a lot of experience with the dual disk system you have. (there is also efibootdump)

    I'm surprised you were able to recover your partitions like you did! Congratulations. Before your "update" I figured you would be toast. I'm afraid I cannot give you any useful advice on Windows. I'm not sufficiently versed. I recently gave up on my Windows VM running under VMWare as some update from Microsoft (or Quicken) rendered the system basically unusable and then led to blue screens on boot with useless messages like "thread exception". I eventually reinstalled completely and lost all of my programs and data, and then the same thing happened anyway. (It also failed in vbox so it is probably Microsoft not vmware.) While I don't see Microsoft as the evil empire any more, I do fault them for any products they use with linux such as a linux host supervisor or skypeforlinux which is a complete walking disaster and ignores bug reports.

    Sorry for digressing. I'm glad you got linux back. You may have some confusion because you may have multiple EFI Partitions. efibootmgr may help you figure that out in conjunction with gparted. Also try sudo fdisk -l


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