[virt-tools-list] [virt-manager PATCH RFC] Remove the difference between VirtIO-SCSI and pure SCSI disks

[Chen Hanxiao]

> -----Original Message-----
> From: virt-tools-list-bounces at redhat.com
> [mailto:virt-tools-list-bounces at redhat.com] On Behalf Of Martin Kletzander
> Sent: Monday, January 27, 2014 10:01 PM
> To: virt-tools-list at redhat.com
> Subject: [virt-tools-list] [virt-manager PATCH RFC] Remove the difference
> between VirtIO-SCSI and pure SCSI disks
> 
> These disk types are differentiated by the *model* of the controller
> they are connected to.  I added a patch that ensures the controller
> which these disk are connected to has model='virtio-scsi', but that is
> breaking libvirt's address generation; having <address
> type='whatever'/> specified makes all unspecified values to fallback
> to zeroes.  Libvirt's address generation is very deterministic (values
> are taken from the disk's target), but will be reliable for an unknown
> period and it's dependant on the order of the controllers.  Other
> thing we can do is not to differentiate between those two and let the
> user decide since the controller model can now be changed using in UI.
> 
> There's bunch of differences between these two approaches, but mainly,
> from code POV I think it is not desirable to show all the disk types
> to the user.  That would mean lots of changes which might not last
> long.  Also we might not be able to guarantee the disk won't be VirtIO
> if the user doesn't select it, e.g. it's the only scsi controller
> available in qemu.  The machine may not start if virtio-scsi
> controller is not available in such qemu OTOH.  My suggestion would be
> to get rid of the differences.  And to see how "huge" the patch would
> be in that case, have a look yourself below (I hope it's correct, it
> works for me at least).
> 

Libvirt will add a scsi controller automatically if we add an scsi disk.
If we want to use a virtio-scsi disk based on your patch, we have to:
1) add a scsi disk
2)modify controller model to virtio-scsi

User may think that would not be convenient.

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