Bug 1301073

Summary:	DM_MULTIPATH_TIMESTAMP among udev properties when device is no longer multipathed
Product:	Red Hat Enterprise Linux 7	Reporter:	mulhern <amulhern>
Component:	device-mapper-multipath	Assignee:	LVM and device-mapper development team <lvm-team>
Status:	CLOSED NOTABUG	QA Contact:	Lin Li <lilin>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.2	CC:	agk, bmarzins, heinzm, lilin, msnitzer, prajnoha
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-02-12 04:16:02 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 mulhern 2016-01-22 14:19:28 UTC

Description of problem:

This value hangs around in a device's udev properties even when device is no longer multipathed. Other DM_MULTIPATH_* values disappear.

Version-Release number of selected component (if applicable):

Name        : device-mapper-multipath
Arch        : x86_64
Version     : 0.4.9
Release     : 85.el7
Size        : 178 k
Repo        : installed
From repo   : RHEL-7

How reproducible:

Seems consistent.

Steps to Reproduce:
1. Remove some multipath devices from a group.
2. Use udevadm to list their udev properties.
3. Notice that DM_MULTIPATH_TIMESTAMP remains even while other DM_MULTIPATH_* properties are gone.

Actual results:

DM_MULTIPATH_TIMESTAMP remains, other DM_MULTIPATH_* properties gone.

Expected results:

I was a little surprised to see any DM_MULTIPATH_* properties remaining for the device.

Additional info:

This may be quite deliberate, but even a reboot doesn't seem to clear it.

Comment 2 Ben Marzinski 2016-02-12 04:16:02 UTC

DM_MULTIPATH_TIMESTAMP will always be there when multipathing is enabled and multipathd is running.  It's purpose it to cut down on how often multipath has to check if a device is a multipath path.  This can take a bit of time, so we don't want to check on every change event.  Instead, multipathd updates a timestamp whenever a new path device is discovered for the first time, or the configuration file is reloaded.  When a change event happens, the device checks its existing timestamp value against the current one, and if it has changed, multipath will recheck the path.