Open Stack

On Fri, Sep 23, 2016 at 07:32:36AM -0500, Matt Riedemann wrote:
> On 9/23/2016 3:54 AM, Daniel P. Berrange wrote:
> > On Thu, Sep 22, 2016 at 01:54:21PM -0500, Matt Riedemann wrote:
> > > Sergey is working on a spec to use the standardized virt driver instance
> > > diagnostics in the os-diagnostics API. A question came up during review of
> > > the spec about how to define a disk 'id':
> > > 
> > > https://review.openstack.org/#/c/357884/2/specs/ocata/approved/restore-vm-diagnostics.rst@140
> > > 
> > > The existing diagnostics code doesn't set a disk id in the list of disk
> > > dicts, but I think with at least libvirt we can set that to the target
> > > device from the disk device xml.
> > > 
> > > The xenapi code for getting this info is a bit confusing for me at least,
> > > but it looks like it's possible to get the disks, but the id might need to
> > > be parsed out (as a side note, it looks like the cpu/memory/disk diagnostics
> > > are not even populated in the get_instance_diagnostics method for xen).
> > > 
> > > vmware is in the same boat as xen, it's not fully implemented:
> > > 
> > > https://github.com/openstack/nova/blob/64cbd7c51a5a82b965dab53eccfaecba45be9c27/nova/virt/vmwareapi/vmops.py#L1561
> > > 
> > > Hyper-v and Ironic virt drivers haven't implemented get_instance_diagnostics
> > > yet.
> > 
> > The key value of this field (which we should call "device_name", not "id"),
> > is to allow the stats data to be correlated with the entries in the block
> > device mapping list used to configure storage when bootin the VM. As such
> > we should declare its value to match the corresponding field in BDM.
> > 
> > Regards,
> > Daniel
> > 
> 
> Well, except that we don't want people specifying a device name in the block
> device list when creating a server, and the libvirt driver ignores that
> altogether. In fact, I think Dan Smith was planning on adding a microversion
> in Ocata to remove that field from the server create request since we can't
> guarantee it's what you'll end up with for all virt drivers.

We don't want people specifying it, but we should report the auto-allocated
names back when you query the data after instance creation, don't we ? If
we don't, then there's no way for users to correlate the disks that they
requested with the instance diagnostic stats, which severely limits their
usefulness.

> I'm fine with calling the field device_name though.


Regards,
Daniel
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