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failed to delete a volume as the backend lv is shown open

asked 2016-01-20 01:13:44 -0500 gravatar image

When deleting a volume which is migrated from another backend to LVM, it fails, and cinder-volume.log shows the backend logical volume is in use, as following:

TRACE oslo.messaging.rpc.dispatcher Stderr: u'File descriptor 7 (/dev/urandom) leaked on lvremove invocation. Parent PID 27071: /usr/bin/python2\n Logical volume cinder-volumes/volume-a7c7ef18-e52f-4149-b610-8a3f1c3751b1 in use.\n'

Using dmsetup and lvs, it is clear that the logical volume is open.

# dmsetup info cinder--volumes-volume--a7c7ef18--e52f--4149--b610--8a3f1c3751b1
Name:              cinder--volumes-volume--a7c7ef18--e52f--4149--b610--8a3f1c3751b1
State:             ACTIVE
Read Ahead:        256
Tables present:    LIVE
Open count:        1
Event number:      0
Major, minor:      253, 8
Number of targets: 1

While, there is no open trace by lsof, so I don't know which process opened the logical volume. Other way to change the open attribute of logical volume is not found yet.

lvchange -an <given lv=""> didn't work. Neither did deleting symlinks to the /dev/dm-* devices. Any information from you is appreciated.

Following are some additional information for reference. Migrating from another backend to LVM backend, the volume is available now, shown as below

90b457db-fc41-412a-a9d2-aef64ac65133 |   available    | cyl-fs

os-vol-mig-status-attr:Name_id shows another id after migration

|     os-vol-mig-status-attr:name_id    | a7c7ef18-e52f-4149-b610-8a3f1c3751b1 |

Information about the backend logical volume by lvs

# lvs | grep a7c7e
  volume-a7c7ef18-e52f-4149-b610-8a3f1c3751b1    cinder-volumes -wi-ao---- 500.00g

Last and not least, not all volumes migrated from another backend to LVM are of such status, among 5 migrated volumes, one volume can be deleted, as its backend logical volume's attributes are -wi-a-----(no open count).

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answered 2016-01-20 02:08:53 -0500 gravatar image

I got it. #finding it is helpful to post question onto this site, even though there is no response yet.

It is related with targetcli.

> ls 
> cd backstore/block
> ls
> delete

Now lvs show the logical volume is not open any longer.

  volume-a7c7ef18-e52f-4149-b610-8a3f1c3751b1    cinder-volumes -wi-a----- 500.00g

I believe it can be deleted now.

While, it's a puzzle that consistency is not well maintained. I suspect there is some issue in Cinder internal.
Another thing to investigate.

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dmsetup is showing my problematic LVM volume as suspended but it is not showing in targetcli console.

dmsetup info /dev/cinder-volumes/volume-f701ec81-aa99-4d82-a742-0c7168e71c7a

Name: cinder--volumes-volume--f701ec81--aa99--4d82--a742--0c7168e71c7a State: SUSPENDED

Gopalakrishnan S gravatar imageGopalakrishnan S ( 2017-07-19 10:27:01 -0500 )edit

Thank you! This is exactly the same problem I was having, and your fix worked!

mojavezax gravatar imagemojavezax ( 2018-09-12 12:42:52 -0500 )edit

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Asked: 2016-01-20 01:13:44 -0500

Seen: 1,624 times

Last updated: Jan 20 '16