Things shouldn't be derived from Error, that is for sure.

Can you verify that it actually works as expected with the change?

Vish

On Nov 16, 2011, at 6:46 AM, Ollie Leahy wrote:

> 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
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> 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>
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/nova/+bug/888649/+subscriptions
> 
> -- 
> You received this bug notification because you are subscribed to
> OpenStack Compute (nova).
> 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>
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/nova/+bug/888649/+subscriptions