[aperi-dev] Re: Aperi R4 - new functionality

["Robert Wipfel" <rawipfel@xxxxxxxxxx>]

>>> On Thu, Oct 11, 2007 at  2:12 PM, in message
<OFC9BAF69B.FB5BC86F-ON87257371.005B6481-86257371.006EF345@xxxxxxxxxx>, Chris
King <chriskng@xxxxxxxxxx> wrote: 

> Thanks for your reply Robert. I found the email in the Aperi archives that

Hi Chris, going to copy aperi-dev for open source etiquette since there's
info here that might be of general interest to the list...

> you referenced in your previous email and have a few follow- up questions (I
> apologize in advance on any dumb questions as I am not familiar with Xen):
> 
> -  What are paravirtualized block devices? Do those devices represent the
> hardware resources made available to guests via a Hypervisor's
> virtualization?

They are disk devices that are presented to Linux guests as /dev/xvd[a-z]

> -  Can Aperi agents discover/probe these block devices under Linux VMs only?

Yes. The code changes were made only for the Linux portions of Aperi.

> -  You mentioned in the email that the Aperi agent (Data agent?) runs inside
> a Xen VM. Where do you install the Aperi agent to discover and probe the
> VM? On the server macine that is being virtualized?

Yes, we treat the virtual machine same as a physical one; so installation of
the Aperi data agent follows the same instructions as for physical. This should
be the case for all virtualization technologies, not just Xen; though the 
other technologies may choose to present virtualized disk devices some other
way. E.g. for the Aperi data agent running on Windows Longhorn server; para
virtualized disks will look completely different I'd think.

> -  How do you select these devices to probe? For example, where do these
> devices appear in the "What to probe" tab of the Create Probe window? Do

Since they're in the model they should, but I've not tried that since I didn't
know about this feature; good question ;-)

> they appear under the "Hypervisors" node/section?

I've not seen this either? Where is the Hypervisors section?

> -  What is the relationship between VMs and Controllers and how they are
> displayed in the Data Manager > Reporting > Asset > By Computer reports? Is
> there one Controller per VM? For example, if a Hypervisor is detected and
> probed, will it have multiple controllers if it has multiple VMs?

For now, the Aperi data model doesn't distinguish VMs from regular
computers - so physical and virtual computers look the same from Aperi's
point of view. Xen Controllers will be discovered by the Aperi data agent
when running inside a Linux (Xen-based virtual) computer.

Thanks,
Robert