it worked I missed the -Zn flag Sent from my iPhone > On 7 Sep 2020, at 21:56, Tomas Dalebjörk <tomas.dalebjork@xxxxxxxxx> wrote: > > 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/
