Bug 1478915 - Nova not using mpath device when using unity cinder plugin for dell_emc
Nova not using mpath device when using unity cinder plugin for dell_emc
Product: Red Hat OpenStack
Classification: Red Hat
Component: openstack-cinder (Show other bugs)
11.0 (Ocata)
All Linux
high Severity high
: ---
: 11.0 (Ocata)
Assigned To: Gorka Eguileor
Avi Avraham
: Unconfirmed, ZStream
Depends On: 1443612
  Show dependency treegraph
Reported: 2017-08-07 09:35 EDT by Jaison Raju
Modified: 2017-09-13 07:49 EDT (History)
7 users (show)

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Last Closed: 2017-08-25 09:28:05 EDT
Type: Bug
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Tracker ID Priority Status Summary Last Updated
Red Hat Knowledge Base (Solution) 3150381 None None None 2017-08-14 02:19 EDT

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Description Jaison Raju 2017-08-07 09:35:54 EDT
Description of problem:
After configuring multipath as per doc for iscsi unity cinder driver , nova is not able to find mpath device for the volume .
The instance ends up getting single path device.

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

How reproducible:
Always in customer environment

Steps to Reproduce:

Actual results:
nova-compute logs that mpath device is not visible although the device is visible in multipath -ll .

Expected results:
nova-compute uses the mpath device for the corresponding volume.

Additional info:
2017-08-06 22:38:26.394 256626 WARNING os_brick.initiator.linuxscsi [req-29b5393b-cbec-468d-ac81-7f7fe666ead4 57ebc072672d48eca08779cec03c3b67 eceeb89ddbaa44bb8fb5db2f935ae9fd - - -] Couldn't find multipath device /dev/mapper/360060160222044002bd07e5933aec3cb

# virsh dumpxml instance-00000009 |grep disk
    <disk type='block' device='disk'>
      <source dev='/dev/disk/by-path/pci-0000:81:00.0-fc-0x500009735018609f-lun-2'/>
      <alias name='virtio-disk0'/>
    <disk type='block' device='disk'>
      <source dev='/dev/disk/by-path/ip-'/>
      <alias name='virtio-disk1'/>
Comment 8 Jaison Raju 2017-08-25 09:29:06 EDT
From what we see, the problem is that the multipath doesn't create any of these 2 symlinks "/dev/mapper/<WWN>" or "/dev/disk/by-id/dm-uuid-mpath-<WWN>",
which are the one os-brick is looking for.

Although in coming releases in Ocata, os-brick will no longer use that mechanism to detect the multipaths.
Once we test & pass this new package via the following bugs, you can confirm the new mechanism will work .

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