[Engine-devel] Empty cdrom drive.

[Igor Lvovsky]

> -----Original Message-----
> From: engine-devel-bounces at ovirt.org
[mailto:engine-devel-bounces at ovirt.org]
> On Behalf Of Livnat Peer
> Sent: Sunday, February 19, 2012 1:07 PM
> To: Dan Kenigsberg
> Cc: engine-devel at ovirt.org; arch at ovirt.org
> Subject: Re: [Engine-devel] Empty cdrom drive.
> 
> On 15/02/12 11:29, Miki Kenneth wrote:
> >
> >
> > ----- Original Message -----
> >> From: "Ayal Baron" <abaron at redhat.com>
> >> To: "Yaniv Kaul" <ykaul at redhat.com>
> >> Cc: engine-devel at ovirt.org
> >> Sent: Wednesday, February 15, 2012 11:23:54 AM
> >> Subject: Re: [Engine-devel] Empty cdrom drive.
> >>
> >>
> >>
> >> ----- Original Message -----
> >>> On 02/15/2012 09:44 AM, Igor Lvovsky wrote:
> >>>>    Hi,
> >>>> I want to discuss $subject on the email just to be sure that we
> >>>> all
> >>>> on the
> >>>> same page.
> >>>>
> >>>> So, today in 3.0 vdsm has two ways to create VM with cdrom :
> >>>>   1. If RHEV-M ask to create VM with cdrom, vdsm just create it
> >>>>   2. RHEV-M doesn't ask to create VM with cdrom, vdsm still
> >>>>   creates
> >>>>   VM with
> >>>>      empty cdrom. Vdsm creates this device as 'hdc' (IDE device,
> >>>>      index 2),
> >>>>      because of libvirt restrictions.
> >>>>      In this case RHEV-M will be able to "insert" cdrom on the
> >>>>      fly
> >>>>      with
> >>>>      changeCD request.
> >>>>
> >>>> In the new style API we want to get rid from stupid scenario #2,
> >>>> because
> >>>> we want to be able to create VM without cdrom at all.
> >>>> It means, that now we need to change a little our scenarios:
> >>>>   1. If RHEV-M ask to create VM with cdrom, vdsm just create it
> >>>>   2. RHEV-M doesn't want to create VM with cdrom, but it want to
> >>>>   be
> >>>>   able to
> >>>>      "insert" cdrom on the fly after this. Here we have two
> >>>>      options:
> >>>>      a. RHEV-M should to pass empty cdrom device on VM creation
> >>>>      and
> >>>>      use
> >>>>         regular changeCD after that
> >>>>      b. RHEV-M can create VM without cdrom and add cdrom later
> >>>>      through
> >>>>         hotplugDisk command.
> >>>>
> 
> 
> The preferred solution IMO would be to let the user choose if he wants a
> VM with CD or not.
> I think the motivation for the above is to 'save' IDE slot if a user
> does not need CD.
> 
> If the user wants to have a VM with CD the engine would create an empty
> CD and pass it to VDSM as a device, but if the user does not require a
> CD there is no reason to create it in VDSM nor in the OE (oVirt Engine).
> 
> Supporting the above requires the engine upgrade to create empty CD
> device to all VMs.
> 

+1  Indeed, this is a right thing to do

> Dan - what happens in 3.0 API if the engine passes the element cdrom but
> with empty path attribute. (I know that if the engine does not pass
> cdrom element VDSM creates empty CD)

We will still create an empty CD

> 



> 
> Livnat
> 
> 
> >>>> Note: The new libvirt remove previous restriction on cdrom
> >>>> devices.
> >>>> Now
> >>>>        cdrom can be created as IDE or VIRTIO device in any index.
> >>>>        It means we can easily hotplug it.
> >>>
> >>> I didn't know a CDROM can be a virtio device, but in any way it
> >>> requires
> >>> driver (which may not exist on Windows).
> >>> I didn't know an IDE CDROM can be hot-plugged (only USB-based?),
> >>
> >> It can't be hotplugged.
> >> usb based is not ide (the ide device is the usb port, the cdrom is a
> >> usb device afaik).
> >>
> >> The point of this email is that since we want to support being able
> >> to start VMs *without* a cdrom then the default behaviour of
> >> attaching a cdrom device needs to be implemented in engine or we
> >> shall have a regression.
> > This is a regression that we can not live with...
> >> In the new API (for stable device addresses) vdsm doesn't
> >> automatically attach a cdrom.
> >>
> >>> perhaps
> >>> I'm wrong here.
> >>> Y.
> >>>
> >>>>
> >>>>
> >>>> Regards,
> >>>>      Igor Lvovsky
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> Engine-devel mailing list
> >>>> Engine-devel at ovirt.org
> >>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
> >>>
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