Re: cloning a disk

On 2026-08-08 00:17, Andy Smith wrote:
>> On Fri, Aug 07, 2026 at 11:34:53PM +0100, mick.crane wrote:
>> > Booting from new clone of OS disk there is kernel panic and fsck
>> > says it's a bit messed up.
> 
> I also meant to ask:
> 
> At what point in the boot process does this kernel panic happen? Is it
> when it tries to find the root filesystem?
> 
> What were the messages from fsck? I appreciate that if this is your 
> only
> computer then they might be
> 
> Thanks,
> Andy

the messages from fsck were about errors fix (yes|no)
I pressed Y key 3 or 4 times then thought "Something went wrong, I 
shouldn't need to do this" and aborted.
nwe mentioned identical uuid on the partitions if both connected and 
hopefully pressing "Y" a couple of times hasn't messed anything up.

This is WITH the cloned disk attached to a USB port via the Startech 
SATA->USB cables
lsblk -o +LOG-SEC
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS     LOG-SEC
sda      8:0    0   2.7T  0 disk                     512
└─sda1   8:1    0   2.7T  0 part /home/mick/WORK     512
sdb      8:16   0 111.8G  0 disk                     512
├─sdb1   8:17   0   976M  0 part /boot/efi           512
├─sdb2   8:18   0 105.1G  0 part /                   512
└─sdb3   8:19   0   5.8G  0 part [SWAP]              512
sdc      8:32   1     0B  0 disk                     512
sdd      8:48   1     0B  0 disk                     512
sde      8:64   1     0B  0 disk                     512
sdf      8:80   1     0B  0 disk                     512
sdg      8:96   0 223.6G  0 disk                     512
├─sdg1   8:97   0   976M  0 part                     512
├─sdg2   8:98   0 105.1G  0 part                     512
└─sdg3   8:99   0   5.8G  0 part                     512
sr0     11:0    1  1024M  0 rom                      512


The sd(c d e f) is likely the old card reader which I thought might as 
well attach inside PC.

root@melon:~# fdisk -l
Disk /dev/sdb: 111.79 GiB, 120034123776 bytes, 234441648 sectors
Disk model: CT120BX500SSD1
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: D97B2271-48BB-4988-BEFA-5153C05D7C94

Device         Start       End   Sectors   Size Type
/dev/sdb1       2048   2000895   1998848   976M EFI System
/dev/sdb2    2000896 222339071 220338176 105.1G Linux filesystem
/dev/sdb3  222339072 234440703  12101632   5.8G Linux swap
The backup GPT table is corrupt, but the primary appears OK, so that 
will be used.


Disk /dev/sda: 2.73 TiB, 3000592982016 bytes, 5860533168 sectors
Disk model: ST3000NM0005-1V4
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: F6A1B30E-8495-8F4B-B53D-4D80D5C28C81

Device     Start        End    Sectors  Size Type
/dev/sda1   2048 5860532223 5860530176  2.7T Linux filesystem
GPT PMBR size mismatch (234441647 != 468862127) will be corrected by 
write.
The backup GPT table is corrupt, but the primary appears OK, so that 
will be used.
The backup GPT table is not on the end of the device.


Disk /dev/sdg: 223.57 GiB, 240057409536 bytes, 468862128 sectors
Disk model:  SA400S37240G
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: D97B2271-48BB-4988-BEFA-5153C05D7C94

Device         Start       End   Sectors   Size Type
/dev/sdg1       2048   2000895   1998848   976M EFI System
/dev/sdg2    2000896 222339071 220338176 105.1G Linux filesystem
/dev/sdg3  222339072 234440703  12101632   5.8G Linux swap
root@melon:~#

-------------

I don't really understand the EFI/GPT to be honest.
The Debian OS disk I left all that to the installer.
I always thought the GPT error message was about the small OS drive but
I disconnected the 3TB drive and commented out its fstab entry and 
rebooted
# fdisk -l
Disk /dev/sda: 111.79 GiB, 120034123776 bytes, 234441648 sectors
Disk model: CT120BX500SSD1
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: D97B2271-48BB-4988-BEFA-5153C05D7C94

Device         Start       End   Sectors   Size Type
/dev/sda1       2048   2000895   1998848   976M EFI System
/dev/sda2    2000896 222339071 220338176 105.1G Linux filesystem
/dev/sda3  222339072 234440703  12101632   5.8G Linux swap
root@melon:~#

There's no message about the backup GPT being corrupted.
So I'm going to assume that the message,
"The backup GPT table is corrupt, but the primary appears OK, so that 
will be used."
Is about the 3TB drive and it's nothing to do with problem cloning the 
OS disk.
As far as I remember when preparing the 3TB drive with fdisk I made a 
new GPT partition table then made a primary partition filling the 
available space.
Perhaps that was an error and you are supposed to leave some space for 
the backup GPT table.
Could some kind soul describe the correct steps for fdisk, mkfs,ext4 a 
disk for GPT with a single primary partition?
Now that I've got the PC open I'll use the internal connections and try 
again to clone the disk with the additional tips people have kindly 
provided.

mick