
Hi Daniel, I was referring to multiple types of controllers. For now, I think it is enough to have only one optional VirtIO-SCSI controller per VM, and (on the ppc64) one obligatory SPAPR VSCSI controller. The main question is how to handle the addresses when the VirtIO-SCSI is disabled and there is only the SPAPR VSCSI controller, and how to handle if the user enables VirtIO-SCSI after the creation of the VM (I think the addresses for the existing disks must remain stable, so the controller index must be 1 for the VirtIO-SCSI and 0 for the SPAPR VSCSI in this case). Do you have any tips on how to implement the disk/cdrom addressing in these cases? Thanks, Vitor
-----Original Message----- From: Daniel Erez [mailto:derez@redhat.com] Sent: terça-feira, 24 de setembro de 2013 09:31 To: Vitor de Lima Cc: engine-devel@ovirt.org Subject: Re: [Engine-devel] Issues with VirtIO-SCSI
----- Original Message -----
From: "Vitor de Lima" <vitor.lima@eldorado.org.br> To: "Daniel Erez" <derez@redhat.com> Cc: engine-devel@ovirt.org Sent: Tuesday, September 24, 2013 12:34:17 AM Subject: RE: [Engine-devel] Issues with VirtIO-SCSI
Hi Daniel,
I asked this question because I have implemented a filter to show only compatible disk interfaces (in change #17964). The main purpose of this patch is to hide the IDE interface type when creating disks for PPC64 VMs (since IDE is not supported on this architecture). If it was decided that the VirtIO-SCSI interface type should be hidden from the user in case it was disabled, I would have to modify that patch a little bit.
For consistency, I'll filter the interface from the list when VirtIO-SCSI is disabled. So yeah, keep that in mind when modifying your patch.
Another issue is that in change #18622 the support for a PPC64-specific controller, the SPAPR VSCSI controller, was introduced. But the code was created based on the assumption that the VirtIO-SCSI controller was always present, and this isn't the case anymore. And another patch that I will work on really soon will add support to create disks that are connected to this interface.
Can you filter the option out or add a warning when VirtIO-SCSI is disabled?
So, I would like some feedback before changing these patches. Is a validation on the backend enough to block the user from using an inexistent
controller?
Should the frontend be changed as well? What would be a good approach to handle multiple SCSI controllers in a VM (were the presence of one of them is optional)?
You should block it in the engine on canDo and filter the option / warn about it in the UI. Regarding multiple controllers, are you referring to multiple types of controllers or just multiple VirtIO-SCSI devices?
Thanks, Vitor
-----Original Message----- From: Daniel Erez [mailto:derez@redhat.com] Sent: segunda-feira, 23 de setembro de 2013 17:06 To: Vitor de Lima Cc: engine-devel@ovirt.org Subject: Re: [Engine-devel] Issues with VirtIO-SCSI
Hi Vitor,
The new VirtIO-SCSI enabled checkbox is an indication whether to attach a VirtIO-SCSI controller when running the VM. It should be enabled automatically on cluster >= 3.3.
When disabled, I think it's preferable not to add a new controller automatically when running the VM as it requires creating/attaching a new VmDevice - which we refrain of on VmInfoBuilder flows (and since it might be confusing to the user...).
As an alternative, I've planned to add a warning in the dialog or create a canDo message to prevent running the VM at all. I'm not sure we should hide the option from disk interfaces list as it's already being filtered using VirtIoScsiEnabled ConfigurationValue (and using OsInfo soon...).
Let me know what you think and thanks a lot for the input!
Daniel
----- Original Message -----
From: "Vitor de Lima" <vitor.lima@eldorado.org.br> To: engine-devel@ovirt.org Sent: Monday, September 23, 2013 10:42:39 PM Subject: [Engine-devel] Issues with VirtIO-SCSI
Hi everyone,
I have found some issues with this patch:
http://gerrit.ovirt.org/#/c/18638/
It allows the user to disable the VirtIO-SCSI disk interface during the VM creation. The problem is that the user still can add, attach and hotplug disks with the VirtIO-SCSI interface type, but when the user does so, libvirt automatically creates a LSI Logic SCSI controller and connects the new disk to it.
How can this problem be solved? Should the VirtIO-SCSI interface type be hidden from the user in case it wasn't enabled, or should the engine enable the VirtIO-SCSI controller, hotplug it, then hotplug the disk into it transparently?
Thanks, Vitor de Lima
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