Open Stack

Hi,

On 8-29-16 13:57, Jens Rosenboom wrote:
> 2016-08-29 11:01 GMT+02:00 Paul Dekkers <paul.dekkers at surfnet.nl>:
>>
>> Hi,
>>
>> Since my fear of backing-file issues I've had years ago with live-migration I always used:
>>
>> force_raw_images=False
>> use_cow_images=False
>>
>> ... on my compute nodes, to have qcow2 instances without backing file. (I'm using ZFS, so deduplication is done on the filesystem anyway.)
>>
>> Using Ubuntu Xenial / Mitaka I found that this does not work as long as the swap backing files aren't created:
>>
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [req-93c219a5-0650-4121-8626-5ad6a319fb73 2476f1b03720446481b793e25277b871 7b109aa61c794259a4c5d6352a3ecaa2 - - -] [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309] Instance failed to spawn
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309] Traceback (most recent call last):
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2218, in _build_resources
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     yield resources
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 2064, in _build_and_run_instance
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     block_device_info=block_device_info)
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2761, in spawn
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     admin_pass=admin_password)
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 3243, in _create_image
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     swap_mb=swap_mb)
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 254, in cache
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     if size > self.get_disk_size(base):
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 308, in get_disk_size
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     return disk.get_disk_size(name)
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/virt/disk/api.py", line 147, in get_disk_size
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     return images.qemu_img_info(path).virtual_size
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]   File "/usr/lib/python2.7/dist-packages/nova/virt/images.py", line 50, in qemu_img_info
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]     raise exception.DiskNotFound(location=path)
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309] DiskNotFound: No disk at /var/lib/nova/instances/_base/swap_2048
>> 2016-08-29 10:24:39.053 30377 ERROR nova.compute.manager [instance: f35abbd1-ef06-4d4d-ab97-b8d79f4ac309]
>>
>> The _base/swap_2048 is created automatically without the two options set.
>>
>> Did anyone stumble upon this before? (Maybe not because there's no default swap in flavors as well as the backing file setting in nova.conf?)
>>
> 
> I have seen this backtrace, but in the context of ephemeral images,
> not swap images, still the root cause looks to be the same. Could you
> check whether the fix in https://review.openstack.org/355415 solves
> the issue for you?

I've changed my line 254 of Xenial/Mitaka's imagebackend.py according to
that patch, and that indeed does solve the issue!

(The base file isn't used or created, but indeed the disk.swap is
allocated instead.)

Regards,
Paul

P.S. I'm reluctant to keep this change though, as I'll probably be
missing Ubuntu's patches on this file, right.