hi I tried all these steps but when I associated the snapshot cow device back to an empty origin, and typed the lvs command the data% output shows 0% instead of 37% ? so it looks like that the lvconvert -s vg1/lvsnap vg1/lv0 looses the cow data? perhaps ypu can guide me how this can be done? btw, just to emulate s full copy, I executed the dd if=/dev/vg0/lv0 of=/dev/vg1/lv0 before the lvconvert -s, to make sure the last data is there and than I tried to mount the vg1/lv0 which worked fine but the data was not at snapshot view even mounting vg1/lvsnap works fine but with wrong data confused over how and why vgmerge should be used as vgsplit does the work? regards Tomas Sent from my iPhone > On 7 Sep 2020, at 18:42, Zdenek Kabelac <zkabelac@xxxxxxxxxx> wrote: > > Dne 07. 09. 20 v 18:34 Tomas Dalebjörk napsal(a): >> thanks for feedback >> so if I understand this correctly >> # fallocate -l 100M /tmp/pv1 >> # fallocate -l 100M /tmp/pv2 >> # fallocate -l 100M /tmp/pv3 >> # losetup —find —show /tmp/pv1 >> # losetup —find —show /tmp/pv2 >> # losetup —find —show /tmp/pv3 >> # vgcreate vg0 /dev/loop0 >> # lvcreate -n lv0 -l 1 vg0 >> # vgextend vg0 /dev/loop1 >> # lvcreate -s -l 1 -n lvsnap /dev/loop1 >> # vgchange -a n vg0 >> # lvconvert —splitsnapshot vg0/lvsnap >> # vgreduce vg0 /dev/loop1 > > > Hi > > Here you would need to use 'vgsplit' rather - otherwise you > loose the mapping for whatever was living on /dev/loop1 > >> # vgcreate vg1 /dev/loop2 >> # lvcreate -n lv0 -l 1 vg1 >> # vgextend vg1 /dev/loop1 > > And 'vgmerge' > > >> # lvconvert -s vg1/lvsnap vg1/lv0 >> not sure if the steps are correct? > > > I hope you realize the content of vg1/lv0 must be exactly same > as vg0/lv0. > > As snapshot COW volume contains only 'diff chunks' - so if you > would attach snapshot to 'different' lv - you would get only mess. > > > Zdenek > _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
