Hello all again, I will answer one of my questions myself as I just found the answer: On Fri, Jan 22, 2016 at 06:18:29PM +0100, Tomas Janousek wrote: > Is there perhaps some way to force the discard manually? I thought that maybe > creating a new sparse file/loop device/physical volume and doing pvmove might > help, but what I got instead was a file that wasn't sparse at all, actually > taking more space than the original one. Is this expected? > (The only explanation I can think of is that pvmove doesn't care nor > understand the on-disk format of device mapper thin-pools so it has to copy > everything byte by byte. Is that it?) > > Maybe creating a sufficiently large volume in the thin pool, doing a dd > if=/dev/zero of=/path/to/volume/tmp/blanks and then deleting > /path/to/volume/tmp/blanks would help, but could be quite slow. :-( This hack with dd if=/dev/zero works indeed, but there's a tool called blkdiscard in util-linux which works much better. I just call it prior to lvremove (or lxc-destroy in my case) and the space is freed. -- Tomáš Janoušek, a.k.a. Pivník, a.k.a. Liskni_si, http://work.lisk.in/ _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
