Bug 1301073 - DM_MULTIPATH_TIMESTAMP among udev properties when device is no longer multipathed
DM_MULTIPATH_TIMESTAMP among udev properties when device is no longer multipa...
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: device-mapper-multipath (Show other bugs)
Unspecified Unspecified
unspecified Severity unspecified
: rc
: ---
Assigned To: LVM and device-mapper development team
Lin Li
Depends On:
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Reported: 2016-01-22 09:19 EST by mulhern
Modified: 2016-02-11 23:16 EST (History)
6 users (show)

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Doc Type: Bug Fix
Doc Text:
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Last Closed: 2016-02-11 23:16:02 EST
Type: Bug
Regression: ---
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RHEL 7.3 requirements from Atomic Host:
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Description mulhern 2016-01-22 09:19:28 EST
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 2016-02-11 23:16:02 EST
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.

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