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

[Chris King <chriskng@xxxxxxxxxx>]

Thanks for the information Robert. I wrote the following high-level overview of the new Xen functionality based on your feedback. Can you review it and provide any feedback on its accuracy and completeness for the R4 release notes?:

"You can now use Aperi Storage Manager to discover and collect data about Xen virtual machines (guests) running
under Linux. Xen is an open source technology that enables you to deploy to Windows and Linux virtual machines using
the Xen Hypervisor and XenBus controller. The Xen Hypervisor is a thin layer of software which can host multiple
virtual machines that run independently of each other while sharing hardware resources.

Install a Data agent on each Linux-based, Xen virtual machine that you want to monitor and then run probes to collect data about
the disk devices presented to those virtual machines. Aperi displays each virtual machine as an explandable node under
Data Manager > Reporting > Asset > By Computer in the navigation tree. Expand a virtual machine's node to view
detailed information about its XenBus controller, disks, and filesystems or logical volumes."

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

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

Sorry, I have my releases mixed up. I don't think there currently is a "Hypervisor" node in the Create Prove > What to Probe tab. I assume that VMs will appear as computers in the "Computers" node on this page for R4.

Thanks.
_________________

Information Development - Aperi
chriskng@xxxxxxxxxx
Aperi: http://www.eclipse.org/aperi/index.php

"Robert Wipfel" <rawipfel@xxxxxxxxxx>

"Robert Wipfel" <rawipfel@xxxxxxxxxx>

10/12/2007 09:49 AM

To	<aperi-dev@xxxxxxxxxxx>, Chris King/Chicago/IBM@IBMUS
cc
Subject	Re: Aperi R4 - new functionality

>>> 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