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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Tue, 03 Sep 2013 09:51:52 +0200
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Subject: Re: [Qemu-devel] [libvirt] [PATCH 3/5] qemu: add usb-bot support
 from disks points of view
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: libvir-list@redhat.com, Guannan Ren <gren@redhat.com>, qemu-devel@nongnu.org

On Mo, 2013-09-02 at 13:57 +0100, Daniel P. Berrange wrote:
> On Mon, Sep 02, 2013 at 05:38:42PM +0800, Guannan Ren wrote:
> > usb-bot only supports 16 luns(0~15) and they must be contiguous,
> > (using lun 0 and 2 without 1 doesn't work). In this case qemu
> > doesn't throw an error, we can not find the lun 2 in guests. So
> > Adding a checking function in libvirt to prevent from this case.
> 
> Hmm, this seems like a problematic restriction.

It's how the hardware works.

> How does this work if we start off a guest with 3 disks
> attached to the usb-bot SCSI controller. Then hot-unplug
> the 2nd disk.

You can't hotplug individual luns anyway.

cheers,
  Gerd