Bug 1163894

Summary:	LVM Thin: Record and display 'origin' and divergence time for thin snapshots
Product:	Red Hat Enterprise Linux 7	Reporter:	Jonathan Earl Brassow <jbrassow>
Component:	lvm2	Assignee:	Peter Rajnoha <prajnoha>
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, prockai, rbednar, thornber, zkabelac
Version:	7.1	Keywords:	FutureFeature
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
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Last Closed:	2017-07-27 16:11:49 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:
Bug Depends On:
Bug Blocks:	1163895, 1295577, 1313485

Description Jonathan Earl Brassow 2014-11-13 16:13:02 UTC

The 'origin' and 'divergence time' of a snap volume should be recorded.
- Initially divergence time is the same as the creation time.
- If origin is deleted; origin should be updated to grand parent (origin -> origin)
divergence time should be updated to the most recent of (divergence time, origin divergence time)

- Show when a snapshot diverged from each of it's ancestors (a tree view would be nice)

Comment 1 Peter Rajnoha 2016-07-20 14:23:34 UTC

This needs to be moved out from 7.3 - we already do have infrastructure for tracking LV ancestry, but we still need a way to track when the snapshot got written first after its creation (and hence tracking the divergence times). Probably requires also support on kernel side.

Comment 2 Peter Rajnoha 2016-07-29 13:19:20 UTC

*** Bug 1240555 has been marked as a duplicate of this bug. ***

Comment 6 Jonathan Earl Brassow 2017-07-27 16:11:49 UTC

(In reply to Peter Rajnoha from comment #1)
> This needs to be moved out from 7.3 - we already do have infrastructure for
> tracking LV ancestry, but we still need a way to track when the snapshot got
> written first after its creation (and hence tracking the divergence times).
> Probably requires also support on kernel side.

I don't see us adding kernel support for a feature like this.  If users can tell when they created a snapshot, that's probably good enough.  If it turns out that customers are clamoring for this feature, we can reopen the bug and determine the best way to proceed.