[et-mgmt-tools] Re: [PATCH]This patch remains the original devices except "disk"

[Daniel P. Berrange]

On Mon, May 28, 2007 at 06:33:13PM +0900, Kazuki Mizushima wrote:
> Hi,
> 
> I make a patch fixed the error when a Original guest has devices, 
> cdrom usb floppy ..., except "disk".
> 
> This patch remains the original devices except "disk". A user can use,
> for example, CD-ROM(floppy etc..) devices in the same way as a Original
> guest in a Cloning guest. I attach the log how the XML is changed before
> and after.

I came across this problem the other day too - I think we should approach
it in a slightly different way though.

Basically a disk can be given to the guest in 3 modes

  - read-only
  - exclusive read-write
  - shared read-write

In the 2nd case, we definitely need to clone the disk. In the 3rd case
we have no need to clone, since if a disk is marked as shared we should
assume the user is doing some kinda of clustering setup. In the 1st
case of read only we also don't neeed to copy the. It may occasionally
be useful to copy  shared or read only disks though, so we should have
an option to override it default behaviour.  eg, if 'hdc' is a readonly
cdrom device, then we could have

   --force-copy=hdc

to request that it be copied, even though it is read only.

So I think we should deal with it thus:

  - If device is read-write                       => copy disk
  - If device is listed with a --force-copy flag  => copy disk
  - If device is read-only                        => don't copy disk
  - If device is shared                           => don't copy disk

Regards,
Dan.
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