[gentoo-user] Trouble with backup harddisks

[tuxic@posteo.de]

Hi,

recently I switched from the old MBR-scheme to GPT on
my new PC.

I have two external USB-harddisk, which were partioned/formatted with
a MBR-scheme/MSDOS partition (but were never used to boot from. They are pure
data containers).

When I connect these to my new PC, only the device is shown:
/dev/sdb, /dev/sdc.

The kernel is configured (beside other things) as follows:

#
# Partition Types
#
CONFIG_PARTITION_ADVANCED=y
# CONFIG_ACORN_PARTITION is not set
# CONFIG_AIX_PARTITION is not set
# CONFIG_OSF_PARTITION is not set
# CONFIG_AMIGA_PARTITION is not set
# CONFIG_ATARI_PARTITION is not set
# CONFIG_MAC_PARTITION is not set
CONFIG_MSDOS_PARTITION=y
# CONFIG_BSD_DISKLABEL is not set
# CONFIG_MINIX_SUBPARTITION is not set
# CONFIG_SOLARIS_X86_PARTITION is not set
# CONFIG_UNIXWARE_DISKLABEL is not set
# CONFIG_LDM_PARTITION is not set
# CONFIG_SGI_PARTITION is not set
# CONFIG_ULTRIX_PARTITION is not set
# CONFIG_SUN_PARTITION is not set
# CONFIG_KARMA_PARTITION is not set
CONFIG_EFI_PARTITION=y
# CONFIG_SYSV68_PARTITION is not set
# CONFIG_CMDLINE_PARTITION is not set
# end of Partition Types

CONFIG_BLOCK_COMPAT=y
CONFIG_BLK_MQ_PCI=y
CONFIG_BLK_MQ_VIRTIO=y
CONFIG_BLK_PM=y

dmesg shows this:
[14617.672363] usb 2-2: New USB device found, idVendor=1058, idProduct=25a2, bcdDevice=10.21
[14617.672364] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[14617.672364] usb 2-2: Product: Elements 25A2
[14617.672365] usb 2-2: Manufacturer: Western Digital
[14617.672366] usb 2-2: SerialNumber: 575844314132383959393934
[14617.681660] usb-storage 2-2:1.0: USB Mass Storage device detected
[14617.681737] scsi host10: usb-storage 2-2:1.0
[14618.725450] scsi 10:0:0:0: Direct-Access     WD       Elements 25A2    1021 PQ: 0 ANSI: 6
[14618.725594] sd 10:0:0:0: Attached scsi generic sg1 type 0
[14618.728090] sd 10:0:0:0: [sdb] Spinning up disk...
[14619.748918] ...ready

I tried different USB ports in a desperate hope of success...
...no, same problem.

Interestingly fdisk shows the following:

host> sudo fdisk -l /dev/sdb
Disk /dev/sdb: 931.49 GiB, 1000170586112 bytes, 1953458176 sectors
Disk model: Elements 25A2   
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: 0x16f2a91f

Device     Boot Start        End    Sectors   Size Id Type
/dev/sdb1           1 1953458175 1953458175 931.5G ee GPT

The type is shown as GPT...but the drive has a MSDOS partition table.

Reading my (old) internal harddrive with an external USB docking
station is possible without any problems, though.

Unfortunatelu I have no space for 1T image of that drive -- otherwise
I would have made an image copy and experiment with that.

So better ask, than sorry.... ;)

Is this fixable or did I lost my backups?

Cheers!
Meino