On 2026-08-08 14:41, Stefan Monnier wrote:
root@melon:~# fdisk -l
Disk /dev/sdb: 111.79 GiB, 120034123776 bytes, 234441648 sectors
[...]
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
[...]
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
The GPT partitioning format keeps 2 copies of the table of partitions:
one
at the beginning of the drive and one at the end, and also the info it
keeps includes the size of the drive. So when you clone to
a differently-sized drive, the 2nd (aka "backup") is inevitably
lost/misplaced. This is normal.
Notice how the "size mismatch (234441647 != 468862127)" mentions
exactly
(well, off-by-one) the sizes of your two drives.
=== Stefan
This is with only the 111GB disk connected.
root@melon:~# 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:~#
-------
This is with only the 2.73TB and the 111GB disk connected.
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.
### (^^^^^^^ I always thought that this message was about the 111GB disk
but now I think it is the fdisk reading first the partition/GPT table of
the 2.73TB disk)
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
root@melon:~#
So now I've diverted from the original "cloning a disk" question and
I've other issues to do with understanding the GPT of disks.
I'm not understanding if the backup GPT Header is on the primary
partition or not.
Perhaps I should have used gdisk instead of fdisk to partition the 2.7TB
disk?
I'm not knowing if after making the GPT table with fdisk then making 1
primary partition on the 2.7TB disk I wrote over the GPT Backup Header.
mick
