[linux-lvm] how to copy a snapshot, or restore snapshot without deleting it

[Davis, Matthew]

Yes that is exactly the option which I would love to have.

Regards,
Matt

-----Original Message-----
From: Zdenek Kabelac [mailto:zkabelac at redhat.com] 
Sent: Monday, 28 January 2019 10:50 PM
To: LVM general discussion and development <linux-lvm at redhat.com>; Zdenek Kabelac <zkabelac at redhat.com>; Davis, Matthew <Matthew.Davis.2 at team.telstra.com>
Subject: Re: how to copy a snapshot, or restore snapshot without deleting it

Dne 21. 01. 19 v 11:32 Zdenek Kabelac napsal(a):
> Dne 18. 01. 19 v 1:53 Davis, Matthew napsal(a):
>> Hi Zdenek,
>>
>> I assumed that LVM thin snapshots would work like git branches.
>> Since git also uses diffs on the backend, and git is popular with 
>> developers, the same kind of behaviour seems reasonable to me.
>>
> 
> Hi
> 
> There is very good reason why the git is not really a good tool for 
> storing binary data...
> 
> Your use-case is 'very specific' sub-case of many different usability 
> scenarios you can do with lvm2 -  so while you might see some 
> potential benefit if the lvm2 would work more closely to git logic, it 
> would look terrible in many other situations.
> 

Hi

Adding some more thoughts here - we can probably give user an option to control this - particularly in this case  - how about something like:

lvconvert --mergesnapshot --keeporigin y|n

so if user would specify 'y' - lvm2 would relink/preserve merged snapshot as an origin for all other existing snapshots of the old origin - this would make more obvious what is going to happen when you start creating and merging lots of them into a single origin.

(yeah - maybe there could be better fitting option name - so it's more about idea here for now)

Zdenek