[linux-lvm] System completely unstable after migrating to thin pools

John Stoffel john at stoffel.org
Fri Dec 4 21:27:11 UTC 2020

>>>>> "Sreyan" == Sreyan Chakravarty <sreyan32 at gmail.com> writes:

Sreyan> On Tue, Dec 1, 2020 at 3:55 AM John Stoffel <john at stoffel.org> wrote:
Sreyan>     I suspect you're toast.  What are you trying to accomplish here
Sreyan>     though?  Trying to stuff 10 pounds of data into a 5 pound bag?  *grin*

Sreyan> I don't know what you mean by that. Do you mean that thin
Sreyan> pools cannot be migrated to from older LVMs ?  

I don't think so.  The two versions of LVM thin pools aren't
compatible.  See the archives of this list for more details.  I also
don't quite trust them either with my data.  

Sreyan>     Or are you trying to have the ability to take snapshots of your system
Sreyan>     to make rollbacks easier? 

Sreyan> Yes.

You might want to think about using 'btrfs' instead, since it supports
filesystem level snapshots, and I think Ubuntu 20.x or newer uses it
for it's default filesystem now.  I'm pretty sure Linux MINT does as

But this will require you to copy the data off the current setup (if
you can get it working again) and onto new disks.  A full re-install
of the OS will be needed.

Not that I truest brtfs either quite yet.  Nor do I like the mashing
of various storage layers into one unified whole (like ZFS does)
though I understand why they feel they need to do it.  

Sreyan>     You need to post the output of your configuration in more detail, with
Sreyan>     dmesg output, logs, lvs, pvs, vgs output, etc.

Sreyan> $ lvs
Sreyan>   LV     VG       Attr       LSize    Pool   Origin Data%  Meta%  Move Log Cpy%Sync Convert
Sreyan>   fedora vgfedora Vwi-aotz--  700.00g pool00        16.66                                  
Sreyan>   pool00 vgfedora twi-aotz-- <929.76g               12.54  16.62                           

So it looks like you're using Fedora, which I honestly don't have alot
of experience with in situations like this.  I'm more of a Debian guy
at home and a CentOS/RHEL guy at work.  

Sreyan> $ pvs
Sreyan>   PV                                                    VG       Fmt  Attr PSize   PFree  
Sreyan>   /dev/mapper/luks-2ec7f1ae-6f9b-4896-a7b2-be7809e9d2f4 vgfedora lvm2 a--  929.99g 120.00m

Sreyan> $ vgs
Sreyan>   VG       #PV #LV #SN Attr   VSize   VFree  
Sreyan>   vgfedora   1   2   0 wz--n- 929.99g 120.00m

Sreyan> dmesg:

Sreyan> https://pastebin.com/raw/svTX92SJ

Sreyan>     But really, you do have backups?

Sreyan> No.

You're probably toast.

Can you boot off a rescue disk, or even a recent Fedora bootable ISO
and poke around at your current setup?  That might let your recover
your data.

Of course before you do that, you should copy the original disk onto a
new disk on save the original somewhere offline and unpowered, so you
can run tests on the copy of the data.

Good luck!

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