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Bug 1164933

Summary: [RFE] LVM Thin: Add ability to import LVs into a thinpool
Product: Red Hat Enterprise Linux 7 Reporter: Jonathan Earl Brassow <jbrassow>
Component: lvm2Assignee: Zdenek Kabelac <zkabelac>
lvm2 sub component: Thin Provisioning QA Contact: cluster-qe <cluster-qe>
Status: CLOSED WONTFIX Docs Contact:
Severity: unspecified    
Priority: unspecified CC: agk, heinzm, jbrassow, msnitzer, prajnoha, thornber, zkabelac
Version: 7.1Keywords: FutureFeature
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
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Clone Of: Environment:
Last Closed: 2020-12-15 07:31:56 UTC Type: Bug
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1119323    

Description Jonathan Earl Brassow 2014-11-17 21:40:50 UTC
Import existing LVs into a thin pool, removing any 'holes' in the process (and deduplicating).
- Take existing LV and existing LV pool.  Append the data extents LV to the pool data.

- Call a script that takes the range of block numbers and adds it to existing thin metadata as a new LV.


Once the LV is in the thin pool, it is possible to discard unused blocks and reclaim them for further use.

Comment 1 Heinz Mauelshagen 2016-10-04 12:47:07 UTC
(In reply to Jonathan Earl Brassow from comment #0)
> Import existing LVs into a thin pool, removing any 'holes' in the process
> (and deduplicating).
> - Take existing LV and existing LV pool.  Append the data extents LV to the
> pool data.
> 
> - Call a script that takes the range of block numbers and adds it to
> existing thin metadata as a new LV.
> 
> 
> Once the LV is in the thin pool, it is possible to discard unused blocks and
> reclaim them for further use.

The to be imported early provisioned LV (i.e. non-thin LV) doesn't have to be inactive during the process, in which case we'd need to add all of its allocated extents to the thin pool, create the fully provisoned thin mapping tree for the LV, update and reload thus trimming the new thin LV as a last step.

For completenes:
in case of such LV being inactive/frozen, we can remove any completely trimmable extents in the first step, thus freeing up space sooner. This approach heavily depends on the locality of any data/metadata on the fatLV relative to the extent size and may result in little early savings worst case.

Comment 4 RHEL Program Management 2020-12-15 07:31:56 UTC
After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.