[linux-lvm] Filesystem corruption with LVM's pvmove onto a PV with a larger physical block size

Ilia Zykov mail at izyk.ru
Tue Mar 5 09:29:27 UTC 2019


>> THAT is a crucial observation.  It's not an LVM bug, but the filesystem
>> trying to read 1024 bytes on a 4096 device.  
> Yes that's probably the reason. Nevertheless, its not really the FS's fault, since it was moved by LVM to a 4069 device.
> The FS does not know anything about the move, so it reads in the block size it was created with (1024 in this case).
> I still think LVM should prevent one from mixing devices with different physical block sizes, or at least warn when pvmoving or lvextending onto a PV with a larger block size, since this can cause trouble.

In this case, "dd" tool and others should prevent too.

Because after:

dd if=/dev/DiskWith512block bs=4096 of=/dev/DiskWith4Kblock

You couldn't mount the "/dev/DiskWith4Kblock" with the same error ;)
/dev/DiskWith512block has ext4 fs with 1k block.

LVM,dd .. are low level tools and doesn't know about hi level anything.
And in the your case and others cases can't know. You should test(if you
need) the block size with other tools before moving or copying.
Not a lvm bug.
Thank you.

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