Dne 5.2.2016 v 12:44 M.H. Tsai napsal(a):
Hi,
Seems that your steps are wrong. You should run thin_repair before
swapping the pool metadata.
Nope - actually they were correct.
Also, thin_restore is for XML(text) input, not for binary metadata
input, so it's normal to get segmentation fault...
"lvconvert --repair ... " is a command wrapping "thin_repair +
swapping metadata" into a single step.
If it doesn't work, then you might need to dump the metadata manually,
to check if there's serious corruption in mapping trees or not....
(I recommend to use the newest thin-provisioning-tools to get better result)
1. active the pool metadata (It's okay if the command failed. We just
want to activate the hidden metadata LV)
lvchange -ay vgg1/pool_nas
2. dump the metadata, then checkout the output XML
thin_dump /dev/mapper/vgg1-pool_nas_tmeta -o thin_dump.xml -r
Here is actually what goes wrong.
You should not try to access 'life' metadata (unless you take thin-pool
snapshot of them)
So by using thin-dump on life changed volume you often get 'corruptions'
listed which actually do not exist.
That said - if your thin-pool got 'blocked' for whatever reason
(deadlock?) - reading such data which cannot be changed anymore could provide
the 'best' guess data you could get - so in some cases it depends on use-case
(i.e. you disk is dying and it may not run at all after reboot)...
I have experience in repairing many seriously corrupted thin pools. If
the physical medium is okay, I think that most cases are repairable.
I also wrote some extension to thin-provisioning-tools (not yet
published. the code still need some refinement...), maybe it could
help.
You should always repair data where you are sure they are not changing in
background.
That's why --repair requires currently offline state of thin-pool.
It should do all 'swap' operations in proper order.
Zdenek
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