[Engine-devel] Low Level design for HotPlug/HotUnplug feature

[Livnat Peer]

On 09/01/12 12:17, Dor Laor wrote:
> On 01/09/2012 11:45 AM, Yaniv Kaul wrote:
>> On 01/09/2012 11:21 AM, Michael Kublin wrote:
>>> Hi, the follow link is providing a low level design for
>>> HotPlug/HotUnplug feature
>>> :http://www.ovirt.org/wiki/Features/DetailedHotPlug  .
>>>
>>> The feature is simple and design is short
>>>
>>> Regards Michael
>>> _______________________________________________
>>> Engine-devel mailing list
>>> Engine-devel at ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>>
>> 1. Corrected some typos, spelling, backend->engine, 'REST API' -> 'API',
>> etc. (didn't fix ' storage procedures' - but I think you've meant
>> 'stored procedures' ?).
>> 2. Missing/questions:
>> - Permissions? Quota?
>> - Explain how disk is created in the first place.
>> - Database (tables, etc.)
>> - Which cluster level is required?
>> - Is it an async or sync task?
>> - Can you plug a system disk?
>> - Can you unplug multiple at a time?
>> - What happens when you plug too many?
>> - How do you determine where (PCI bus-wise) to plug them?
>> - Any CanDoAction to allow/disallow plug/unplug from specific systems?
>> - I suspect we'd be happier with some agent cooperation before
>> unplugging - is this done by QEMU? Not detailed anywhere.
>> - Link to KVM/QEMU feature description for it, if such exist, would be
>> nice.
>> - Does it affect taking a snapshot? Live or not?
>> - Does it affect exporting a VM? I reckon you export with all disks,
>> with their plug/unplug status?
> 
> In addition:
>  - will you allow it during live migration (qemu allows it)?
>  - Are you expecting events to pop?
>  - You call it 'hotplug' but mention only disk device, what about
>    memory/cpu/ any other pci card?
>  - How do you define a system disk? Some VM may boot from
>    pxe/nfsroot/etc
>  - It should be a nice to have to check if the guest mounts any FS
>    within the disk to be un hot pluged and warn the user
> 

In addition - 2 :

- plugged/unplugged  disk is a VM property not disk's. (this of a shared
disk that can be plugged in one VM but unplugged in another)

- supporting the best effort flag is not related only to hot plug disk,
is it supported in the VDSM level on a per disk basis? again should not
be a disk property but a VM-Disk relation property.


>>
>> Y.
>>
>>
>>
>>
>>
>>
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>> http://lists.ovirt.org/mailman/listinfo/engine-devel
> 
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