On Tue, Apr 10, 2018 at 09:47:30AM +0100, Richard W.M. Jones wrote:
> Recently in Fedora something changed that stops us from creating small
> LVs for testing.
> 
> An example failure with a 64 MB partitioned disk:
> 
> # parted -s -- /dev/sda mklabel msdos mkpart primary 128s -128s
> Warning: The resulting partition is not properly aligned for best 
> performance: 128s % 65535s != 0s
> # lvm pvcreate --force /dev/sda1
>   /dev/sda1: Data alignment must not exceed device size.
>   Format-specific initialisation of physical volume /dev/sda1 failed.
>   Failed to setup physical volume "/dev/sda1".

Interestingly the alignment properties of the virtio-scsi virtual disk
has changed.  On the working system:

==> /sys/block/sda/queue/minimum_io_size <==
512

==> /sys/block/sda/queue/optimal_io_size <==
0

On the new / broken system:

==> /sys/block/sda/queue/minimum_io_size <==
33553920

==> /sys/block/sda/queue/optimal_io_size <==
0

(all other settings were the same).  I suppose this accounts for it,
and it could therefore be a problem with qemu rather than LVM.

Working: qemu-2.11.0-4.fc28.x86_64
Broken:  qemu-2.12.0-0.5.rc1.fc29.x86_64

Alasdair Kergon asked me to run the lvm command with -vvvv and I've
attached those results.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org

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