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@redhat.com> To: Motohiro Kawahito <JL25131@jp.ibm.com> Cc: libvir-list@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@redhat.com> To: Motohiro Kawahito <JL25131@jp.ibm.com> Cc: libvir-list@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.