I've tracked down the source of the problem deleting volumes that are 
    referenced by snapshots using nova.volume.ISCSIDriver.

    When the driver detects that the volume is busy then the delete_volume() 
    method in the VolumeDriver class in nova/volume/driver.py raises a 
    VolumeIsBusy exception with a keyword arg.  However, the VolumeIsBusy 
    exception is derived from Error in nova/exception.py and neither 
    VolumeIsBusy nor Error accept keyword parameters. This means that an 
    unexpected keyword exception is raised, which the driver doesn't expect so 
    it sets the status of the volume to 'error-deleting' and stops. See the log 
    fragment below.


    Deleting volumes works if I change nova/exception.py so that the 
    exception VolumeIsBusy derives from NovaException instead of Error.  
    NovaException can handle keyword arguments, so VolumeDrive.delete_volume() 
    sees the exception is expects (VolumeIsBusy) and it can handle the 
    situation correctly.

    Any opinions on whether this is the 'correct' way to fix this problem?

    regards,
    Ollie


    



2011-11-16 11:06:46,211 DEBUG nova.utils [-] Running cmd (subprocess): sudo lvdisplay --noheading -C -o Attr nova-volumes/volume-000000a4 from (pid=6234) execute /usr/lib/python2.7/dist-packages/nova/utils.py:165
2011-11-16 11:06:46,271 ERROR nova.volume.manager [-] driver raised exception <__init__() got an unexpected keyword argument 'volume_name'>
2011-11-16 11:06:46,296 ERROR nova.rpc [-] Exception during message handling
(nova.rpc): TRACE: Traceback (most recent call last):
(nova.rpc): TRACE:   File "/usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py", line 620, in _process_data
(nova.rpc): TRACE:     rval = node_func(context=ctxt, **node_args)
(nova.rpc): TRACE:   File "/usr/lib/python2.7/dist-packages/nova/volume/manager.py", line 189, in delete_volume
(nova.rpc): TRACE:     raise
(nova.rpc): TRACE: TypeError: exceptions must be old-style classes or derived from BaseException, not NoneType
(nova.rpc): TRACE:


# diff -c /usr/share/pyshared/nova/exception.py{,.backup}
*** /usr/share/pyshared/nova/exception.py   2011-11-16 11:46:31.000000000 +0000
--- /usr/share/pyshared/nova/exception.py.backup    2011-11-16 11:39:04.000000000 +0000
***************
*** 370,376 ****
      message = _("Snapshot %(snapshot_id)s could not be found.")
  
  
! class VolumeIsBusy(NovaException):
      message = _("deleting volume %(volume_name)s that has snapshot")
  
  
--- 370,376 ----
      message = _("Snapshot %(snapshot_id)s could not be found.")
  
  
! class VolumeIsBusy(Error):
      message = _("deleting volume %(volume_name)s that has snapshot")
  


-----Original Message-----
From: Leahy, Oliver 
Sent: 15 November 2011 14:35
To: 'Bug 888649'
Subject: RE: [Bug 888649] [NEW] Snapshots left in undeletable state

On my installation I can delete a volume that is referenced by a 
snapshot. I will try to understand why this is so and get back to 
you.

Though as I said in my previous message the behavior of the LVM based 
driver is different to the behavior I described in my original bug 
report.


Regards,
Ollie

-----Original Message-----
From: <email address hidden> [mailto:<email address hidden>] On Behalf Of Isaku Yamahata
Sent: 14 November 2011 19:06
To: Leahy, Oliver
Subject: Re: [Bug 888649] [NEW] Snapshots left in undeletable state

On Thu, Nov 10, 2011 at 05:43:59PM -0000, Ollie Leahy wrote:
> $ euca-create-volume -s 1 -z nova
> VOLUME	vol-0000007c	1	creating (bocktest, None, None, None)	2011-11-10T17:36:41Z
> # euca-create-snapshot vol-0000007c
> SNAPSHOT	snap-00000018	vol-0000007c	creating	2011-11-10T17:37:33Z	0%
> # euca-delete-volume vol-0000007c# euca-delete-volume vol-0000007c
> VOLUME	vol-0000007c

This volume in LVM with snapshot shouldn't be deleted
with VolumeIsBusy exception.
(At least it's my intension of VolumeDriver::delete_volume() with lvdisplay)
Can you please track down why it can be deleted?

If this volume in LVM is deleted, the all of derived snapshots are
deleted at the same time. So the following lvremove for snapshot
would fail. It explains the below behavior.

thanks,
-- 
yamahata

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report.
https://bugs.launchpad.net/bugs/888649

Title:
  Snapshots left in undeletable state

Status in OpenStack Compute (Nova):
  New

Bug description:
  If a volume is created using the euca api,
                       then a snapshot is created from the volume
                       then the volume is deleted
  the snapshot cannot now be deleted. If the user tries
  to delete the snapshot it ends up in the state 'error_deleting'
  and remains in the system.

  The following sequence of euca commands illustrates the problem

  $ euca-create-volume -s 1 -z nova
  VOLUME	vol-0000007c	1	creating (bocktest, None, None, None)	2011-11-10T17:36:41Z
  # euca-create-snapshot vol-0000007c
  SNAPSHOT	snap-00000018	vol-0000007c	creating	2011-11-10T17:37:33Z	0%
  # euca-delete-volume vol-0000007c# euca-delete-volume vol-0000007c
  VOLUME	vol-0000007c
  # euca-delete-snapshot snap-00000018
  SNAPSHOT	snap-00000018
  # euca-describe-snapshots 
  SNAPSHOT	snap-00000018	vol-0000007c	error_deleting	2011-11-10T17:37:33Z	100%
  # euca-delete-snapshot snap-00000018
  Traceback (most recent call last):
    File "/usr/bin/euca-delete-snapshot", line 110, in <module>
      main()
    File "/usr/bin/euca-delete-snapshot", line 101, in main
      return_code = euca_conn.delete_snapshot(snapshot_id)
    File "/usr/lib/pymodules/python2.7/boto/ec2/connection.py", line 1112, in delete_snapshot
      return self.get_status('DeleteSnapshot', params)
    File "/usr/lib/pymodules/python2.7/boto/connection.py", line 648, in get_status
      raise self.ResponseError(response.status, response.reason, body)
  boto.exception.EC2ResponseError: EC2ResponseError: 400 Bad Request
  <?xml version="1.0"?>
  <Response><Errors><Error><Code>ApiError</Code><Message>Snapshot status must be available</Message></Error></Errors><RequestID>286ce49b-3c6d-4dcb-8130-52afe8b9ba94</RequestID></Response>

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