Re: Question about skipping virDomainDiskDefAssignAddress

Laine Stump <laine(a)laine.org&gt; wrote on 2021/07/17 00:01:36: > From: Laine Stump <laine(a)laine.org&gt; > To: Libvirt <libvir-list(a)redhat.com&gt; > Cc: Motohiro Kawahito <JL25131(a)jp.ibm.com&gt;, "Daniel P. Berrangé" > <berrange(a)redhat.com&gt; > 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(a)redhat.com&gt; > >>> To: Motohiro Kawahito <JL25131(a)jp.ibm.com&gt; > >>> Cc: libvir-list(a)redhat.com > >>> 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(a)redhat.com&gt; > >>>>> To: Motohiro Kawahito <JL25131(a)jp.ibm.com&gt; > >>>>> Cc: libvir-list(a)redhat.com > >>>>> 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