Re: [Xen-users] How to list the drives a DomU is using, and their types -- with or without a parition -- from the Dom0?

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Feb 16, 2016 at 06:04:13AM -0800, billb@xxxxxxx wrote:
> 
> 
> On Tue, Feb 16, 2016, at 03:22 AM, Roger Pau Monné wrote:
> > Try xl block-list $DOMU?
> 
> That gives you something like
> 
> xl block-list 6
> Vdev  BE  handle state evt-ch ring-ref BE-path                       
> 768   0   6      4     16     8        /local/domain/0/backend/vbd/6/768
> 832   0   6      4     17     9        /local/domain/0/backend/vbd/6/832
> 
> How do map those BE-paths to a /dev/disk or /dev/mapper path that I can use 
> in an lvcreate command at the Dom0?
> 

Hmm... Right, it is not immediately visible to end user.

You can then use the BE-path to do

  xenstore-ls -f /local/domain/0/backend/vbd/6/768/

and

  xenstore-read /local/domain/0/backend/vbd/6/768/params

.

It's a bit cumbersome, but at least now you know all knobs related to
this disk.

> > This is not specific to Xen. I guess you can write a script to parse
> > output from "kpartx -l"?
> 
> Ok, so nothing in the xen info has 'knowledge' about thar?  I have to test & 
> see, once I have the disk path?
>

The hypervisor and the backend don't know what the frontend does to
its disk -- they don't care and shouldn't care. Parsing output from
kpartx is the right solution.

> > Why don't you just snapshot the whole volume, even if it has partitions
> > inside?
> 
>  I want to tar.gz the result.  IIUC, I need the contents for that, right?
> 

If you want to extract the files from its file system, sure. But if
all you want is a disk image, you can just take a snapshot of that
disk image.

Wei.

> Bill

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