Q and A on Xen Presentation

Where would you use live migration?
   Disaster planning, load balancing, quick scaling to handle increased
   load.

Explain what 'Native' means.
   OS installed without Xen directly on the hardware.
   'Virtual' means running under Xen

How does the partition look to the guest OSes?
   The partition looks like a whole disc drive to the guest instance. 

How does Xen do with accessing the HW? Sometimes VMWare/Windows has trouble
reaching the parallel port.
   Worse than VMWare by quite a bit.  VMWare proxies the hardware really
   well.
   It can see Network, disc, and a Video graphics adaptor
   USB, printers, not well supported. Network printers supported.
   Guest OS access to 'unproven' hardware that the base OS doesn't even
   see. Used for developing drivers for new hardware.
   Betters for servers not desktops.
   Networking very well supported. Multiple IP addresses.

Can you run OSX as a guest OS?
   Eventually.

Can you use Xen to run old DOS games?
   Probably not.
   DOSemu/DOSbox
   Wine?
   QMU

How can you find out if your processor supports VT?
   Looking at the box when you buy it. It says 'virtual' on the front.
   Motherboard support for VT needed as well. Look in the BIOS for VT
   enable/disable.

Can 2 different Xen guest instances talk to each other?
   Through the network, yes.
   Working on special network filesystem for Xen hosts.
   Network Block Device in the host system's RAM.

12 full motion video streams. Any advantage to using virtualization to
display video when you need to do database access at the same time as
streaming video?
   The display on a virtual machine will be slower
   Low latency networking would provide some speed gains.

Using Xen as a 'virtual firewall' for my small office?
   And Asterisk on another virtual?
   Yes, absolutely!
   Asterisk would need PCI direct access, which is supported, in order to
   access the Plain Old Telephone System.

Accounting software, sensitive financials on a virtual machine that doesn't
have network support. (Single machine airgap network)
  How secure is it?
  Would a guest OS be able to get to the data? yes.
  Better than nothing, but not perfect.
  It's important to keep sensitive applications separate from more 'lax'
  security applications.

How much space do you need for a Xen instance? Is it Fixed or Dynamic?
  Minimum system requirements.
  50-100megabytes for small Linux install.
  2 Virtuals on 1Ghz Celeron.
  Depends on what you're doing with it.
  Lots of processing power applications will need more Processor speed, and
  perhaps more RAM.
  Xen is pretty low overhead, so you don't need to add a lot of hardware
  just to handle the virtualization.
  10 or 20 instances on a single server run quite well.

  Balloon RAM allocation, can resize RAM on the fly.
  The drive looks like a regular drive, so you can set up a swap partition
  if you want.

Does each machine need it's own screen?
   Serial console
   Graphics console running under VNC
   Linux doesn't require a console.

Visual machine?
  Virtual machine.
  Are they one person, one system?
  Not unless you want it to be.

What guest OS can Xen run unmodified?
  with VT support yes,
  without, not.

  look at the partition table on a running Xen instance

Why Xen?
  Seperation of services for ease of SysAdmin.
  Testing and development of new software.
  Reduce number of physical computers, reduce power use, reduce waste.