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

L A Walsh lvm at tlinx.org
Sat Mar 2 01:37:47 UTC 2019

On 2/27/2019 9:05 AM, Ingo Franzki wrote:
> Yes that should work:
> # losetup -fP loopbackfile.img --sector-size 4096
> # blockdev --getpbsz /dev/loop0
> 4096
Something I noticed that is troublesome.  When I first got my 4K sectory
size disks, one of the numbers in the kernel listed it as 4K, now ~4-5
years later, that difference no longer appears in the kernel!  To me, this
seems a bit unwise -- as even though these disks are "512_e_"  (a 512 byte
sector size can be emulated but writes will usually or often take a minimum
of 2 revolutions so that the rest of the 4k sector can be read, have
updated, then write the whole 4k sector size out.  In otherwords -- hideous
performance on writes. 

Now the RAID controller that manages this disk also has info on the
disks -- and
there it correctly shows the 4k sector size.  So am wondering what in
the kernel
"broke"(?) to disable detection & display of its native 4k sector size.

Anyway, I don't think it should cause problems unless I reformat or move the
partitions,  but it would be nice to know the various disk software knows
not to try anything smaller than a 4k sector size.

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