Re: pvmove thin volume doesn't move

[David Teigland <teigland@redhat.com>]

On Sun, Nov 16, 2025 at 08:27:30AM -0500, Brian J. Murrell wrote:
> Hi.
> 
> I've added a new (faster) disk to a VG and now want to move a thinly
> provisioned LV to the new PV.  When I try it doesn't find any data to
> move though:
> 
> # pvmove -n /dev/rootvol_tmp/var /dev/sda7 /dev/sdc
>   No data to move for rootvol_tmp.

Thanks for asking, one of the reasons we don't really have a plan for
this, or other things, is that we just don't get users asking for much.
Over the past couple years I've actually noticed a lot of people looking
to copy LVs, and even some external tools that have been written to do it.
There's quite a bit of variation though, and it's often copying over the
network, or recently, copying on a SAN so another host can use the LV.
There has been some work in our group aimed at parts of the problem,
for example https://github.com/device-mapper-utils/blk-archive

So, it's been at the front of mind that LV copying in some fashion is one
of the larger missing features.  What's not clear to me is if we can find
a solution that meets enough of the varied use cases, but I'll try to
raise more discussion about it.

Dave