Laine Stump <laine@xxxxxxxxx>
wrote on 2021/07/17 00:01:36:
> From: Laine Stump <laine@xxxxxxxxx>
> To: Libvirt <libvir-list@xxxxxxxxxx>
> Cc: Motohiro Kawahito <JL25131@xxxxxxxxxx>,
"Daniel P. Berrangé"
> <berrange@xxxxxxxxxx>
> Date: 2021/07/17 00:01
> Subject: [EXTERNAL] Re: Question
about skipping virDomainDiskDefAssignAddress
>
> On 7/16/21 8:51 AM, Daniel P. Berrangé wrote:
> > On Fri, Jul 16, 2021 at 09:49:40PM +0900, Motohiro Kawahito wrote:
> >>> From: "Daniel P. Berrangé" <berrange@xxxxxxxxxx>
> >>> To: Motohiro Kawahito <JL25131@xxxxxxxxxx>
> >>> Cc: libvir-list@xxxxxxxxxx
> >>> Date: 2021/07/16 17:22
> >>> Subject: [EXTERNAL] Re: Question about skipping
> >> virDomainDiskDefAssignAddress
> >>>
> >>> On Fri, Jul 16, 2021 at 01:01:50PM +0900, Motohiro Kawahito
wrote:
> >>>>> From: "Daniel P. Berrangé" <berrange@xxxxxxxxxx>
> >>>>> To: Motohiro Kawahito <JL25131@xxxxxxxxxx>
> >>>>> Cc: libvir-list@xxxxxxxxxx
> >>>>> Date: 2021/07/16 00:42
> >>>>> Subject: [EXTERNAL] Re: Question about skipping
> >>>> virDomainDiskDefAssignAddress
> >>>>>
> >>>>
> >>>>> With the exception of paravirtualized Xen guests,
this field in
> >>>>> libvirt XML is *completely* independant of the
guest assigned
> >>>>> device name.
> >>>>>
> >>>>> eg the XML might say /dev/vda, but the guest
might decde to
> >>>>> call it /dev/sda, or /dev/whatever or really
absolutely
> >>>>> anything.
> >>>>
> >>>> Thank you very much for this information! I understand
it.
> >>>> However, I don't understand how we can pass the target
device
> >> information
> >>>> (e.g. 0A80) without an error. Do you know how to
do it?
> >>>>
> >>>> My question was not good, so I opened another thread
(How do we
> >> specify
> >>>> disk device names for non-Linux VMs in XML?).
> >>>
> >>> There is nothing that needs passing. The guest OS decides
its naming
> >>> however it wants to.
> >>
> >> We need to control device number from user. This device number
would be
> >> used later, such as detach-disk. Can we pass device number
from outside?
> >
> > Detach-disk requires the same information that is provided when
the
> > disk is first configured in libvir. This is completely separate
to the
> > device number / name seen inside the guest.
>
> To expand on that, in the case of detaching a disk, you could 1) provide
> the target dev in the XML you give to "virsh detach-device",
2) give the
> target dev name that you provided in the original XML when you call
> "virsh detach-disk", or 3) you could specify a custom alias
in the
> original XML ("<alias name='ua-somename'/>" - note
that the leading
> "ua-" is *required* for a custom alias name) and then give
that same
> alias to "virsh detach-device-alias". All three will allow
you to
> reliably select the disk you want, and have the same result.
>
Laine and Daniel,
thank you very much for your comments. It's good to know the flexibility
in the naming convention. However, I found libvirtd rejects a non-Linux
device (i.e. '0A84') as a target device. The following two commands return
an error message, "Unknown disk name '0A84'". Can you let me
know how we specify an unusual name, like '0A84'?
$ virsh attach-disk
sample_domain /volumes/user.qcow2 0A84
$ virsh detach-disk
sample_domain 0A84
If we should use
an alias, could you advise me how to specify? Thank you so much again for
your help.
