error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

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videoguy
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error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

Post by videoguy »

Hello,
I've got a problem with not being able to boot into Windows 10 or Linux Mint on my computer. Here are my system specs. Processor:AMD Ryzen 9 3600X. Motherboard:MSI B350 Tomahawk. Ram:16 GB Corsair Vengeance 2800Mhz. Graphics Card:4GB Nvidia Geforce GTX 1050 Ti. Storage: ADATA SU650 (240GB),Kingston A400 M.2 SATA SSD (240GB), Western Digital WD20EZRZ-22Z (2TB), Seagate Firecuda ST4000DX005 (4TB). Operating System: Windows 10 Pro 64-bit .Linux mint (20.1?), Cinnamon. (I can't boot into windows or linux mint so I can't give a more detailed OS Version.

A couple years ago I built this computer and dual-boot installed Windows 10 and Linux Mint. A couple months ago I noticed a Kingston M.2 SSD on my motherboard. I guess I must have forgot I put it there. Yesterday I was looking at E: drive, the drive letter for the Kingston M.2 SSD (240GB). I noticed it said it was 520MB in size or so, and (if I remember) it was empty. I figured it must have been improperly formatted/partitioned, so I used the Windows 10 Disk Management Application to make some changes. I remember 2 partitions being there and about 130GB of Unallocated Free Space. The 2 partitions didn't seem important, and since I believed I had installed both Windows and Linux on the ADATA 240GB SSD I figured I could safely delete them. I believe that was my mistake. Do'h! Don't partition hard drives when you're very tired. I don't remember what the 2 partitions were called but I have partitioned drives enough to read their labels and they didn't seem important. I then make a new simple volume, gave it E: drive letter, and voilà! Windows File Explorer showed a Kingston 240ish GB ssd empty and ready for use. I shut down my computer and went to sleep. This morning I turn on my computer and find this error message on boot.

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error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. 
error: unknown filesystem.
Entering rescue mode... grub rescue>
I looked up solutions online. I tried using grub rescue to search for a /grub directory, but every entry I tried

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ls (hd0)
turned up unknown filesystem. I made a bootable USB with Linux Mint and tried using a tool called Boot Repair, with "recommended repair". Still can't boot, but I believe the error message changed to something else, sorry I can't really reproduce or remember the grub error message. Boot repair does have a Bootinfo summary. It's hosted here: http://sprunge.us/1g5FCJ It's really quite long and I don't think I should post the text here.
here is the result of the command fdisk:

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mint@mint:~$ sudo fdisk -l
Disk /dev/loop0: 2.1 GiB, 2251292672 bytes, 4397056 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/sda: 3.64 TiB, 4000787030016 bytes, 7814037168 sectors
Disk model: ST4000DX005-3GH1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: D36FC982-036E-40D4-9C5C-9A1AFBBCA459

Device     Start        End    Sectors  Size Type
/dev/sda1     34      32767      32734   16M Microsoft reserved
/dev/sda2  32768 7814033407 7814000640  3.6T Microsoft basic data

Partition 1 does not start on physical sector boundary.


Disk /dev/sdb: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: WDC WD20EZRZ-22Z
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x65a679eb

Device     Boot Start        End    Sectors  Size Id Type
/dev/sdb1  *     2048 3907026943 3907024896  1.8T  7 HPFS/NTFS/exFAT


Disk /dev/sdc: 223.57 GiB, 240057409536 bytes, 468862128 sectors
Disk model: ADATA SU650     
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x28b27fe1

Device     Boot   Start       End   Sectors  Size Id Type
/dev/sdc1  *       2048   1126399   1124352  549M  7 HPFS/NTFS/exFAT
/dev/sdc2       1126400 468858879 467732480  223G  7 HPFS/NTFS/exFAT


Disk /dev/sdd: 223.57 GiB, 240057409536 bytes, 468862128 sectors
Disk model: KINGSTON SA400M8
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xdb9cb791

Device     Boot Start       End   Sectors   Size Id Type
/dev/sdd1        2048 468858879 468856832 223.6G  7 HPFS/NTFS/exFAT


Disk /dev/sde: 28.64 GiB, 30752636928 bytes, 60063744 sectors
Disk model: Ultra           
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 6D4F3559-353E-4F68-9E80-073EBFC45977

Device       Start      End  Sectors  Size Type
/dev/sde1       64  4709379  4709316  2.2G Microsoft basic data
/dev/sde2  4709380  4717875     8496  4.1M EFI System
/dev/sde3  4718592 60063680 55345089 26.4G Linux filesystem


I didn't save a backup image or anything of the Kingston SSD before I changed it. My system is backed up cloud offsite, so I should be okay whatever the outcome. Any advice on what to do next? Any helpful details I can add to get closer to a solution? Thanks!
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JerryF
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Re: error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

Post by JerryF »

Word of advice: don't rely on Windows Disk Management to view disks/partitions because Windows doesn't support EXT4 so it doesn't show a formatted partition that it recognizes.

Use Gparted to view, and manipulate partitions.
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zcot
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Re: error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

Post by zcot »

So, drive e. looks like it had the mint system on it, you can see the entry from that boot log.

The original partition uuid was the one you mention in your post title.

You formatted that drive.

Now there's a new partition there with that new uuid mentioned in the fdisk output.

In theory, all the old stuff is still there sitting like it was, but you changed the partition table in the mbr to now a newly fresh other partition situation. If you could only get back your previous mbr table and rewrite it back onto that disk it would be fine.

If you've written a bunch of stuff onto that drive then the previous info under the new writes is gone/damaged/corrupted. But that's just the files space so maybe nothing important being lost? Most likely not good at all, but maybe it only clobbered 1 small unused file?

If you have a copy of the old table, that works, rewrite it.

Here's some example of a situation like that, this is an ubuntu guide to use testdisk so you would have to just get the general idea from it, but you can do that same thing from the mint live disk: https://linuxconfig.org/how-to-recover- ... e-in-linux

I would look around a little bit, don't write anything on that drive, don't touch it, don't view it, don't even open any file manager, don't even think about it, and then check for some guides about using testdisk and restore that partition table.

quick search for restore partition table using testdisk, another result:
https://www.cgsecurity.org/wiki/TestDisk_Step_By_Step
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videoguy
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Re: error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

Post by videoguy »

I tried using Testdisk to find any lost partition tables on that Kingston E: drive but no luck. It only shows 1 partition, that being NTFS which is what windows uses. Interestingly, the Boot Repair Tool says that Syslinux is installed on the sdb volume.

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 => Windows 7/8/10/11/2012 is installed in the MBR of /dev/sda.
 => Syslinux MBR (5.00 and higher) is installed in the MBR of /dev/sdb.
 => Grub2 (v2.00) is installed in the MBR of /dev/sdc and looks at sector 1 of 
    the same hard drive for core.img. core.img is at this location and looks 
    for /boot/grub. It also embeds following components:
If I were to keep scanning all the volumes and found a deleted MBR, what would it look like? I've read that it should be 512 bytes. For future readers, these 2 documents were very helpful to understand a bit about partitions, file systems, booting, etc. https://access.redhat.com/documentation ... itions-x86https://www.freecodecamp.org/news/file- ... explained/ Being unable to access Windows 10 was a huge downer for me because I use it to edit videos and do my job. Future readers should know about a tool called Super Grub 2 Disk. It let me bypass...whatever exactly is keeping me from booting. I got access to windows and that takes a lot of pressure off me to take the time to figure this out.
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Re: error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

Post by zcot »

the Kingston is d in your output from the first post, and the boot repair info shows the same.

The drives can change at times depending on which first boot drive you have in order and how you're viewing the info, although generally are in motherboard connection order. If you're booting directly off a d drive then on that system d is considered a.

The MBR is a boot code and then a partition table. You only want the partition table. If you replaced the boot code that could mean a different issue, although that's not hard to overcome putting grub back in shape, but the preferred thing is just regain the partition table.

The previous info shows GRUB installed in multiple locations so it very well could be booting from c, but that would just mean that it then chainloads to the one on d.

If you install or have installed multiple linux systems and on different drives then updating grub will make them recognize each other and update their grub menu to include the other systems on any other locations.

What you want, is to be able to recover the partition table on that kinston drive. It doesn't matter if it's currently recognized as a b c d or whatever, you have to address that kingston and make sure you are focused on that one if you can get any success.
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Re: error: no such device: c6891cc6-28c5-45a0-aa79-52967027bc7a. error: unknown filesystem. Entering rescue mode.

Post by mikeflan »

Being unable to access Windows 10 was a huge downer for me because I use it to edit videos and do my job.
Consider making a full disk image of any disk (drive) you consider to be very important to you. If you have the disk space to store the image it is good insurance against failures. It might take a couple hours to restore it and restore recent backups, but it is a good option to have.
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