Hi, I am trying to understand how to convert a disk containing snapshot data. This is how I tested this: 1. locate the snapshot testlv.211218.232255 root@debian10:/dev/mapper# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert home debian10-vg -wi-ao---- 1.00g root debian10-vg -wi-ao---- <3.81g swap_1 debian10-vg -wi-ao---- 976.00m testlv debian10-vg owi-aos--- 100.00m testlv.211218.232255 debian10-vg swi-a-s--- 104.00m testlv 1.44 root@debian10:/dev/mapper#
2. copy the lv - cow data to a file # dd if=/dev/mapper/debian10--vg-testlv.211218.232255-cow of=/tmp/out bs=1024 3. Setup a loopback disk for the file # losetup -fP /tmp/out 4. Verify that disk exists root@debian10:/dev/mapper# losetup -a /dev/loop0: [65025]:39274 (/tmp/out) root@debian10:/dev/mapper# 5. Try converting the disk using lvconvert command # lvconvert -Zn -s debian10-vg/testlv /tmp/out "/tmp/out": Invalid path for Logical Volume. 6. Trying creating a softlink in /dev/mapper # ln -s /tmp/out debian10--vg-loopback 7. verify link root@debian10:/dev/mapper# ls -la total 0 drwxr-xr-x 2 root root 240 Dec 19 17:40 . drwxr-xr-x 18 root root 3820 Dec 19 17:22 .. crw------- 1 root root 10, 236 Dec 10 19:10 control lrwxrwxrwx 1 root root 7 Dec 10 19:10 debian10--vg-home -> ../dm-5 lrwxrwxrwx 1 root root 8 Dec 19 17:40 debian10--vg-loopback -> /tmp/out lrwxrwxrwx 1 root root 7 Dec 13 22:20 debian10--vg-root -> ../dm-1 lrwxrwxrwx 1 root root 7 Dec 10 19:10 debian10--vg-swap_1 -> ../dm-4 lrwxrwxrwx 1 root root 7 Dec 18 23:23 debian10--vg-testlv -> ../dm-0 lrwxrwxrwx 1 root root 7 Dec 18 23:23 debian10--vg-testlv.211218.232255 -> ../dm-6 lrwxrwxrwx 1 root root 7 Dec 18 23:23 debian10--vg-testlv.211218.232255-cow -> ../dm-3 lrwxrwxrwx 1 root root 7 Dec 18 23:23 debian10--vg-testlv-real -> ../dm-2 root@debian10:/dev/mapper# 8. retrying lvconvert command root@debian10:/dev/mapper# lvconvert -Zn -s debian10-vg/testlv /dev/mapper/debian10--vg-loopback Failed to find logical volume "debian10-vg/loopback" root@debian10:/dev/mapper# Are there more things to be considered, such as recreating pv data on disk? Regards Tomas
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