[libvirt] [libvirt-users] [RFC] per-device metadata

[Francesco Romani]

(CC devel list - better late than never)


On 03/16/2017 04:23 PM, Daniel P. Berrange wrote:
> On Thu, Mar 16, 2017 at 04:17:51PM +0100, Peter Krempa wrote:
>> On Thu, Mar 16, 2017 at 14:52:47 +0000, Daniel Berrange wrote:
>>> On Thu, Mar 16, 2017 at 03:50:51PM +0100, Peter Krempa wrote:
>>>> On Thu, Mar 16, 2017 at 14:42:30 +0000, Daniel Berrange wrote:
>>>>> On Thu, Mar 16, 2017 at 01:46:38PM +0100, Peter Krempa wrote:
>>>>>> On Mon, Feb 27, 2017 at 16:41:28 +0100, Francesco Romani wrote:
>> [...]
>>
>>> The scenario where device attach fails is not the problem - you can
>>> get the same level of reliabilty to that by simply updating the
>>> global metadata before & after hotplug in the same way. What is
>>> difficult is when libvirt fails to persist the XML config on disk
>>> or when libvirt crashes part way through the operation, and other
>>> akward failure scenarios unrelated to QEMU itself.
>> In that case you lose the device definition too, since saving the XML is
>> the integral part of the hotplug operation.
> Agreed, but that just re-inforces my view that we don't need to provide
> extra metadata against the device for sake of atomicity. Even the existing
> hotplug doesn't guarantee any kind of atomicity, so you're not making life
> worse by performing a separate API call to update the global metadata.
>
>
> Regards,
> Daniel

Thanks everyone,  I will file a bug so we can move forward on this.

Bests,

-- 
Francesco Romani
Red Hat Engineering Virtualization R & D
IRC: fromani