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

[Michael Kublin]

----- Original Message -----
> From: "Livnat Peer" <lpeer at redhat.com>
> To: "Michael Kublin" <mkublin at redhat.com>
> Cc: dlaor at redhat.com, "Yaniv Kaul" <ykaul at redhat.com>, engine-devel at ovirt.org
> Sent: Monday, January 9, 2012 3:07:06 PM
> Subject: Re: [Engine-devel] Low Level design for HotPlug/HotUnplug feature
> 
> 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' ?).
Thanks
> >> 2. Missing/questions:
> >> - Permissions? Quota?
Regards Quota - has not influence on the feature
> >> - Explain how disk is created in the first place.
The disk is added to VM by AddDiskToVMCommand, by default is is plugged
> >> - Database (tables, etc.)
They are in design
> >> - Which cluster level is required?
Added to design , it is 3.1
> >> - Is it an async or sync task?
Sync
> >> - Can you plug a system disk?
No
> >> - Can you unplug multiple at a time?
Yes, we have not such limitation, the sane is to plug.
> >> - What happens when you plug too many?
We allow to plug disk which were attached to vm , by AddDiskToVmCommand, a max number of allowed disks is handled there
> >> - How do you determine where (PCI bus-wise) to plug them?
As I think, the PCI address will be added to most devices at Stable PCI device addresses feature, I will use it 
> >> - Any CanDoAction to allow/disallow plug/unplug from specific
> >> systems?
The operation will be allowed only for RHEL 5/6, Windows Server 2003 and Windows server 2008 operating systems, added to design
> >> - I suspect we'd be happier with some agent cooperation before
> >> unplugging - is this done by QEMU? Not detailed anywhere.
I will check this 
> >> - Link to KVM/QEMU feature description for it, if such exist,
> >> would be
> >> nice.
> >> - Does it affect taking a snapshot? Live or not?
No, all disk will be passed to snapshots as is
> >> - Does it affect exporting a VM? I reckon you export with all
> >> disks,
> >> with their plug/unplug status?
This one I need to check
> > In addition:
> >  - will you allow it during live migration (qemu allows it)?
I don't see any technical limitation from my side, but I will check
> >  - Are you expecting events to pop?
> >  - You call it 'hotplug' but mention only disk device, what about
> >    memory/cpu/ any other pci card?
The pci card it is another feature, in current version we have only hotplug / unplug for disks and pci card 
> >  - How do you define a system disk? Some VM may boot from
> >    pxe/nfsroot/etc
I had a property on the disk which means System, also I have a property that means bootable. I suppose that 
disk can not be plugged/unplugged with any of them 
> >  - 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
Need to be check
> 
> 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)
Ok. I will update design
> - 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.
> >>
> >>
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> Engine-devel mailing list
> >> Engine-devel at ovirt.org
> >> http://lists.ovirt.org/mailman/listinfo/engine-devel
> > 
> > _______________________________________________
> > Engine-devel mailing list
> > Engine-devel at ovirt.org
> > http://lists.ovirt.org/mailman/listinfo/engine-devel
> 
>