[linux-lvm] Repair thin pool

Joe Thornber thornber at redhat.com
Wed Feb 10 10:32:49 UTC 2016

On Tue, Feb 09, 2016 at 02:03:39AM +0800, M.H. Tsai wrote:
> 2016-02-08 16:56 GMT+08:00 Joe Thornber <thornber at redhat.com>:
> > On Fri, Feb 05, 2016 at 07:44:46PM +0800, M.H. Tsai wrote:
> >> I also wrote some extension to thin-provisioning-tools (not yet
> >> published. the code still need some refinement...), maybe it could
> >> help.
> >
> > I'd definitely like to see what you changed please.
> >
> > - Joe
> I wrote some tools to do "semi-auto" repair, called thin_ll_dump and
> thin_ll_restore (low-level dump & restore), that can find orphan nodes
> and reconstruct the metadata using orphan nodes. It could cope the cases
> that the top-level data mapping tree or some higher-level nodes were
> broken, to complement the repairing feature of thin_repair.
> Although that users are required to have knowledge about dm-thin metadata
> before using these tools (you need to specify which orphan node to use), I
> think that these tools are useful for system administrators. Most thin-pool
> corruption cases I experienced (caused by power lost, broken disks, RAID
> corruption, etc.) cannot be handled by the current thin-provisioning-tools
> --  thin_repair is fully automatic, but it just skips broken nodes.
> However, those missing mappings could be found in orphan nodes.
> Also, I wrote another tool called thin_scan, to show the entire metadata
> layout and scan broken nodes. (which is an enhanced version of
> thin_show_block in branch low_level_examine_metadata -- I didn't notice
> that before... maybe the name thin_show_block sounds more clear?)
> What do you think about these features? Are they worth to be merged to the
> upstream?

Yep, I definitely want these for upstream.  Send me what you've got,
whatever state it's in; I'll happily spend a couple of weeks tidying

- Joe

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