This external western digital hard drive installed in an enclosure, is connected with eSATA to a 2012 Dell XPS desktop computer. This hard drive is fairly new as I got it early this year. And so when I try to boot up my Mint 19.2 on a 50 GB partition formatted by the MBR method not GPT, it gives error; "kernel panic not syncing- VFS: unable to mount root fs on unknown block (0,0). And I am booting other Linux installed on a internal drive okay with the Windows 7. And a 2ND error which sounds alike; " attempt to read or write outside of disk hd0. So is possibly a defective hard drive or does it need a full reformat? When I run the sudo fdisk -l from a good booting other Linux, it does show all 8 partitions okay except for the sector size; ( other drives have both listed as 512 bytes ), this drive has;
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
So why is that?

How did you install Mint on the external drive? What bootloader does it use? Grub on a bios/mbr device requires it's own little partition.

Show fdisk -l or parted -l for the external drive.
Then post the grub config for it. What file system is on that external drive?

james2b,

I suspect that your boot partition is full of old Linux kernels.

You can test this by booting from your original installation media (live DVD/USB). Do not install Mint.

Menu > Terminal and run:

Then run:

What are the outputs?

""kernel panic not syncing- VFS: unable to mount root fs on unknown block"

This I see when the boot process is not correct. For example booting to a usb flash drive but you really need to boot to a hard drive choice that is a usb.

I partitioned and then formatted the external drive from my Windows 7, and then for Linux I used the EaseUS Partition Master. But then the fdisk -l showed some error messages about; "Partition does not start on physical sector boundary, for all 7 partitions. So to fix this issue I booted to a good Linux installed on an internal solid state drive, Ubuntu Mate 18.04, then I opened and used the GParted tool to delete and then re-create at the same size all the partitions, which did correct that issue. So then I did a new install of the Mint 19.2 over the old install which worked and booted okay at first, but then got those other boot errors latter. I installed from the iso file image on the live DVD, and chose to install the grub boot loader onto MBR of that external drive,( it gives an error when attempting to put grub onto the Mint partition boot sector. Do I need to make a separate partition just for grub? I have the Easy BCD in my 7 to configure the Windows boot loader with the primary Linux booting from grub on the internal drive with Mate 18.04.

james2b@james2b-XPS-8500:~$ sudo fdisk -l
[sudo] password for james2b:
Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 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
Disklabel type: dos
Disk identifier: 0x231e48dd

Device Boot Start End Sectors Size Id Type
/dev/sda1 63 80324 80262 39.2M de Dell Utility
/dev/sda2 * 81920 32940031 32858112 15.7G 7 HPFS/NTFS/exFAT
/dev/sda3 32940032 1953521663 1920581632 915.8G 7 HPFS/NTFS/exFAT


Disk /dev/sdb: 111.8 GiB, 120034123776 bytes, 234441648 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
Disklabel type: dos
Disk identifier: 0xe66a4f8e

Device Boot Start End Sectors Size Id Type
/dev/sdb1 * 2048 104855563 104853516 50G 83 Linux
/dev/sdb2 104856256 230676479 125820224 60G 83 Linux
/dev/sdb3 230676480 234440703 3764224 1.8G 82 Linux swap / Solaris


Disk /dev/sdc: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
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: 0x8312bb41

Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 692062207 692060160 330G 7 HPFS/NTFS/exFAT
/dev/sdc2 692062208 901793791 209731584 100G 7 HPFS/NTFS/exFAT
/dev/sdc3 * 901793792 1006659583 104865792 50G 83 Linux
/dev/sdc4 1006659584 1953523711 946864128 451.5G 5 Extended
/dev/sdc5 1006661632 1111527423 104865792 50G 83 Linux
/dev/sdc6 1111529472 1216395263 104865792 50G 83 Linux
/dev/sdc7 1216397312 1249951743 33554432 16G 82 Linux swap / Solaris
/dev/sdc8 1249953792 1953523711 703569920 335.5G 7 HPFS/NTFS/exFAT

So the sda and sdb are internal drives, and the external is sdc with some Linux as EXT3 and the problem Mint 19.2 as EXT4, also some NTFS for Windows partitions.

At the grub menu hightlight the linux mint entry, press e for edit, and post what you see.

Okay I did that and got a picture of it but due to file size too big I can not attach it. insmod part_msdos, insmod ext2, set root= 'hd2,msdos3', then there is a if then statement that is all technical and then last 2 lines; linux /boot/vmlinuz-4.15.0-66-generic root=UUID=(numbers and letters), initrd /boot/initrd.img-4.15.0-66-generic. I may just buy a new Samsung 500 GB solid state drive and attempt to install it inside my external enclosure, (data and power connections should line up).

You have 3 50GB partitions on the drive. Is linux mint on the third parition of the drive? Compare the uuid from the following.
to the root=uuid=<some number> on the linux line of the grub menu and see if they match

What is this error?

Another thought, are you booting the external mint from the internal mint grub?
If so have you ran from the internal mint?

It was booting from the internal drive Mate 18.04 grub and from the Easy BCD Windows boot manager tool. What I did was give up on it and assumed that Western Digital hard drive was defective. So I removed it from the external enclosure and deleted all the partitions, and then did a RMA back to the company. They sent me a recertified replacement drive which I have not yet opened and used. Is that type of hard drive just as good as new? Okay thanks for all the help.