[Engine-devel] Empty cdrom drive.

Yaniv Kaul ykaul at redhat.com
Wed Feb 15 09:13:02 UTC 2012


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.
>
> 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?), perhaps 
I'm wrong here.
Y.

>
>
> Regards,
>      Igor Lvovsky
>
>
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