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Groups > linux.debian.user > #265915

512e vs 4K sector confusion

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Hi,

I've got a disk image that sits on top of an LVM logical volume
that is on top of an mdadm RAID-1 that is on top of a pair of:

Device Model:     Samsung SSD 870 EVO 4TB
Sector Size:      512 bytes logical/physical

so let';s say that is at /dev/foo/disk_image (where /dev/foo is the
name of the LVM VG and disk_image is the LV)

So,

# fdisk -ul /dev/foo/disk_image
Disk /dev/foo/disk_image: 400 GiB, 429496729600 bytes, 838860800 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: 0x14409245

Device                            Boot Start       End   Sectors  Size Id Type
/dev/foo_disk_image                    2048 838858751 838856704  400G 83 Linux

So it's a 400G disk image with an MBR and a single partition, right?

Now, I dd that disk image across the network to another machine
which has a similar setup, except here the "foo" volume group is on
a pair of

Device Model:     HGST HUS726T6TALN6L4
Sector Size:      4096 bytes logical/physical

Now, after the disk_image has arrived, it looks very odd. fdisk
thinks it is 8 times bigger than it really is, and thinks it has 4K
sectors. I can't use "kpartx" to get at the partition inside it, and
fsck.ext4 doesn't like its first partition at all.

Is there any way to make this work?

If necessary and if there is a way, I *can* nuke off the target
machine's "foo" volume group and recreate the RAID array if I have
to make it 512e format. But obviously I'd like some way to move this
disk image and have it still work without having to meddle inside it
much — it is a VM disk.

Thanks,
Andy

-- 
https://bitfolk.com/ -- No-nonsense VPS hosting

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512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-14 09:10 +0100
  Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-14 09:20 +0100
    Re: 512e vs 4K sector confusion "Alexander V. Makartsev" <avbetev@gmail.com> - 2024-01-14 12:30 +0100
    Re: 512e vs 4K sector confusion Arno Lehmann <al@its-lehmann.de> - 2024-01-14 12:40 +0100
  Re: 512e vs 4K sector confusion "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-14 14:30 +0100
    Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-14 17:20 +0100
      Re: 512e vs 4K sector confusion "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-14 18:00 +0100
  Re: 512e vs 4K sector confusion Timothy M Butterworth <timothy.m.butterworth@gmail.com> - 2024-01-14 19:20 +0100
  Re: 512e vs 4K sector confusion Stefan Monnier <monnier@iro.umontreal.ca> - 2024-01-15 05:40 +0100
    Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-15 06:40 +0100
      Re: 512e vs 4K sector confusion Nicolas George <george@nsup.org> - 2024-01-15 22:30 +0100
      Re: 512e vs 4K sector confusion Nicholas Geovanis <nickgeovanis@gmail.com> - 2024-01-15 22:30 +0100
        Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-16 01:40 +0100
        Re: 512e vs 4K sector confusion Teemu Likonen <tlikonen@iki.fi> - 2024-01-16 17:40 +0100
      Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-17 08:30 +0100
  Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-20 22:30 +0100

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