Bug 905028

Summary:	[RFE] Avoid reading devices we know to fail
Product:	[Community] LVM and device-mapper	Reporter:	Zdenek Kabelac <zkabelac>
Component:	lvm2	Assignee:	LVM and device-mapper development team <lvm-team>
lvm2 sub component:	Filtering and Stacking	QA Contact:	cluster-qe <cluster-qe>
Status:	CLOSED WONTFIX	Docs Contact:
Severity:	unspecified
Priority:	unspecified	CC:	agk, bmarzins, bmr, dwysocha, heinzm, jbrassow, jonathan, lvm-team, msnitzer, prajnoha, zkabelac
Version:	2.02.166	Keywords:	FutureFeature
Target Milestone:	---	Flags:	rule-engine: lvm-technical-solution? rule-engine: lvm-test-coverage?
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Enhancement
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-06-29 20:52:03 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Zdenek Kabelac 2013-01-28 12:13:05 UTC

Description of problem:

With lvm2 with have several cases, when we could skip reading/checking devices we may know we shouldn't read.

There are several scenarios were we are trying to i.e. check for metadata on devices, they are not readable or should not be scanned.

Here are 2 examples -

1st. activate thin pool device - scanning such volume has no use - since thin pool has no header - and thus it presents it self as a device with 'mixed' signatures - i.e. block zero could be from any thin volume which happend 
to allocate this block - as well as the block at the end of this device.

2nd. reading invalid snapshot results in error read.
(Bug 839811 comment 6)

Both cases depend on the scan order - but if we know metadata ahead of touching
this device - we may potentially have good chance to skip scanning them.



Version-Release number of selected component (if applicable):
lvm2-2.02.98-4.fc19.x86_64

How reproducible:


Steps to Reproduce:
1.
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Actual results:


Expected results:


Additional info:

Comment 1 Fedora End Of Life 2013-04-03 16:01:38 UTC

This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle.
Changing version to '19'.

(As we did not run this process for some time, it could affect also pre-Fedora 19 development
cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.)

More information and reason for this action is here:
https://fedoraproject.org/wiki/BugZappers/HouseKeeping/Fedora19

Comment 2 Zdenek Kabelac 2013-10-22 08:47:09 UTC

This bug is getting to be more important since i.e. thin-pool might be in failed stated....

Comment 3 Alasdair Kergon 2016-10-11 22:56:33 UTC

Scanning needs refinement.

Comment 4 Jonathan Earl Brassow 2020-06-29 20:52:03 UTC

FWIW, we now have 'scan_lvs = 0' as default.  Will close this bug and ask to direct any new conversation or ideas to opt-in filters and SID work.