[linux-lvm] how to copy a snapshot, or restore snapshot without deleting it
zkabelac at redhat.com
Thu Jan 17 09:21:55 UTC 2019
Dne 17. 01. 19 v 2:12 Davis, Matthew napsal(a):
> Hi Zdenek,
> What do you mean "it's origin is already gone"?
Your field 'Origin' in your 'lvs -a' was empty - so the actual origin used for
taking 'fresh' LV snapshot is simply no longer existing.
lvm2 is (ATM) not a database tool trying to resolve/guess what can or cannot
be still considered as the origin - so i.e. if you take multiple snapshots of
a single origin and then you merge one snapshot back to origin - 'the
original origin' used for all other snapshots is 'gone' - as lvm2 is not
resolving here the history and relation of data content whether the meaning of
origin still applies.
What can make sense in your case is to extend probably 'lvconvert' logic and
provide operation i.e. --replace - which would be working mostly like merge
- but with thins you would be able to specify which thinLV should replace
some other thinLV so basically specifying replace LV1 with LV2 - which you can
do by lvremove + lvrename ATM - but I can see usefulness for supporting this
for i.e. root LV which is typically in-use all the time.
I'm not seeing possible to extended the internal logic in lvm2 that would be
deciding which NEW origin should be replacing removed/merged origin in all
related snapshots - I'm pretty sure every user would expect a different one...
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