I have created a thin volume in a Qnap NAS (TS-230 with QTS 4.5.2 ). I have put some files on it. There are no valuable data included. I am just doing a disaster recovery training.
I have installed mdadm and assembled RAID
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mdadm --assemble --scan
mdadm: /dev/md/9 has been started with 1 drive (out of 64).
mdadm: /dev/md/1 has been started with 1 drive.
mdadm: /dev/md/13 has been started with 1 drive (out of 64).
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lvscan
WARNING: Unrecognised segment type tier-thin-pool
WARNING: Unrecognised segment type flashcache
WARNING: PV /dev/md1 in VG vg1 is using an old PV header, modify the VG to update.
LV tp1, segment 1 invalid: does not support flag ERROR_WHEN_FULL. for tier-thin-pool segment.
Internal error: LV segments corrupted in tp1.
Cannot process volume group vg1
When I have created a thick volume the result was the same (with an extra warning mentioning ‘thick’).
It is obvious that the cause of the problems is not corruption but incompatibility.
There is a chance ([SMB] HOW-TO RECOVER data from LVM volume on a PC (UX-500P)) that the problem can be overcame with using thin-provisioning-tools, but this exceeded my abilites.
I have also made and an attempt with Recovery Explorer Standard and the trial version was able to discover files (scanning 8TB Seagate IronWolf Pro took 10 hours). So there is a good chance of successful recovery (and $39 is much less than any commercial recovery service).
The current conclusion is that there is no simple way to recover data from a thin (thick) volume.
When you are looking for a decision which type of volume to use (like me), this problem is a good point for Static Volume.