The backup GPT table is corrupt, but the primary appears OK, so that will be used.

On 8/8/26 05:07, mick.crane wrote:
 > root@melon:~# fdisk -l
 > ...
 > 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>
 > 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.


I agree -- fdisk(8) is printing the error message before listing the 3 
TB HDD partition table.


I had a 3 TB HDD that was producing the same error.  I fixed it with 
gdisk(8):

2021-10-29 22:22:16 root@dipsy ~/hardware/seagate/ST3000DM001-REDACTED
# gdisk /dev/disk/by-id/ata-ST3000DM001-REDACTED
GPT fdisk (gdisk) version 1.0.3

Caution: invalid backup GPT header, but valid main header; regenerating
backup header from main header.

Partition table scan:
   MBR: protective
   BSD: not present
   APM: not present
   GPT: damaged

****************************************************************************
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk
verification and recovery are STRONGLY recommended.
****************************************************************************

Command (? for help): p
Disk /dev/disk/by-id/ata-ST3000DM001-REDACTED: 5860533168 sectors, 2.7 TiB
Sector size (logical/physical): 512/4096 bytes
Disk identifier (GUID): REDACTED
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 2925 sectors (1.4 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
    1            2048      5860532223   2.7 TiB     A504  z3000a

Command (? for help): v

No problems found. 2925 free sectors (1.4 MiB) available in 2
segments, the largest of which is 2014 (1007.0 KiB) in size.

Command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to 
/dev/disk/by-id/ata-ST3000DM001-REDACTED.
The operation has completed successfully.


David