[linux-lvm] [dm-devel] fix corrupted thin pool

[Zdenek Kabelac]

Dne 27.10.2014 v 07:58 Anatoly Pugachev napsal(a):
> On Sun, Oct 26, 2014 at 1:47 AM, Zdenek Kabelac <zkabelac at redhat.com
> <mailto:zkabelac at redhat.com>> wrote:
>  >
>  > Dne 25.10.2014 v 22:53 Vasiliy Tolstov napsal(a):
>  >>
>  >> 2014-10-26 0:18 GMT+04:00 Zdenek Kabelac <zkabelac at redhat.com
> <mailto:zkabelac at redhat.com>>:
>  >>>
>  >>> There is 'internal' metadata archive then -
>  >>>
>  >>> dd if=/dev/your_pv_volume  of=/tmp/1st.megabyte   bs=1M count=1
>  >>>
>  >>> It's will capture first megabyte of your PV where are embedded
>  >>> metadata of your Volume group.
>  >>>
>  >>> If you are not skilled enough - tar.gz and send this file to me.
>  >>
>  >>
>  >>
>  >> I'm do dd and send it. While i'm break thin pool i'm try to restore volume
> 2657.
>  >> But i don't stop lvm thin pool =(.
>  >>
>  >
>  >
>  > From the metadata  something bad was going one:
>  >
>  > Fri Oct 24 17:03:04 2014
>  >
>  > transaction_id = 120  - create = "3695"
>  >
>  > And suddenly on Fri Oct 24 18:07:23 2014
>  > pool is back on older transaction_id
>  >
>  > transaction_id = 114
>  >
>  >
>  > Is that the time of your vgcfgrestore?
>  >
>  > I'm attaching those metadata which you likely should put back to get in sync
>  > with your kernel metadata (assuming you have not modified those in any way)
>
> Zdenek,
>
> can you please describe (possibly in details) what have you done with tar.gz
> sent to you, so everyone would know what to do next time?
>
> Thanks a lot!


Any Google query on lvm2 metadata recovery will disclose this - I've picked 
randomly this one:
http://microdevsys.com/wp/linux-lvm-recovering-a-lost-volume/


In this case however provided data by user were just too short since he 
created 300M metadata space - so I've asked to resend 4M on my email - so you 
will not exactly find the info above in the initial tar.gz file (there
are just older versions) - but if you open  file in 'vi' editor - you will see 
those metadata yourself.

Zdenek