[Cialug] Next AmesLUG topic

[Don Ellis]

When talking about VirtualBox, be sure and mention vboxtool, which wraps the
CLI for VBox and makes it much easier to start VMs from the command line
and/or with init.d scripts.

    http://vboxtool.sourceforge.net/

Mostly developed for Ubuntu, but also works well in other hosts.

When installing in CentOS (either host or guest), you will need to install
developer tools (cpp and kernel module requirements) in order to use Guest
Additions.

Installing in OpenSUSE is a bit cleaner; it allows selecting cpp and kernel
module stuff during initial system install (CentOS has been crashing for me
if I select any additional packages -- any clues?)

One egregious error in vboxtools: you are supposed to be able to change the
RDT port in the vboxtools config file, but there is a syntax error in the
script. I plan to correct the error (in my ample spare time ;-) ), but have
just not been playing with that feature so far. A couple of other errors,
too, but not too bad, once you learn what is really required.

One more item: if you start a VM with vboxtool, you will only be able to
start up a GUI with RDT; the VBox GUI mostly shows VM status in this mode.
You can, however, save the state of a VM from the command line and restore
it from the GUI, and vice versa.

I'll pass on more notes, if anyone is interested in running VBox headless
(or CLI controlled).

--Don Ellis


On Wed, Sep 15, 2010 at 9:13 AM, Daniel A. Ramaley <daniel.ramaley at drake.edu
> wrote:

> On 2010-09-14 at 17:05:55, murraymckee at wellsfargo.com wrote:
> >Why would you chose one VM over another?
>
> Different virtual machine technologies are suited for different tasks. I
> help maintain the Xen cluster at work, but use VirtualBox on my personal
> machines. Xen is very well-suited to large installations that are
> running many VMs as always-on servers, VirtualBox is well-suited to
> running the occasional VM on my desktop (great for testing and for the
> errant Windows app).
>
> For the remainder of these questions, i'll assume we are talking about
> desktop-side virtualization (VirtualBox, Parallels, VMWare Workstation,
> ec.) since that seems to suit your level of knowledge better. (Please
> pardon the presumption... or if not, feel free to flame me.) If you want
> to discuss server-side virtualization (Xen, KVM, VMWare Server), then
> most of these answers would be very different.
>
> >       What are the strong & weak points of the various VMs?
>
> Mostly this would depend on if you're talking desktop or server style
> virtualization. Within those 2 spheres, however, strong & weak points
> tend to be similar.
>
> Some VM architectures have more overhead than others, or allow VMs to
> run faster than others. Or support different operating systems (either
> for host or guest). Or are Free versus proprietary. If you have
> something specific in mind that you want to do, i'm sure someone could
> recommend a good VM architecture to start with. Personally i'd recommend
> VirtualBox since it is easy to install and the documentation is easy to
> follow (read the entire User Manual... it's worth the time to gain
> understanding how VM stuff works).
>
> >What do they cost to install?  Purchase price / disk space / etc.
>
> Depends on which one. Some are free. Disk space for the VM architecture
> itself is usually minimal on modern hardware (a few MB to a couple GB).
>
> >What do they cost to run?  CPU / Memory / etc.
>
> The VM software itself doesn't use much in the way of resources. The VMs
> running within it, however, will certainly need some CPU and RAM. My
> machine at work has a dual-core CPU with 4 GB RAM. At home i have a
> dual-core with 8 GB RAM. I've never had any problem running several VMs
> on either machine, though if i have the VMs doing any serious number
> crunching i'd probably want more CPU available.
>
> >How do you install it?  Guest OS and then VM or vice versa
>
> Most desktop VM architectures install like any other application. Many
> install kernel drivers which may or may not require a reboot, depending
> on which host OS you're on.
>
> For a desktop VM architecture, you install your host OS first, then the
> VM software, then whatever guest OSes you intend to use.
>
> >Any special considerations to installing an OS as a guest rather than
> >a base OS?
>
> If you're installing something esoteric, check the compatibility list
> for the VM software first. If your guest OS is not listed, that doesn't
> mean you are out of luck, just that you're diving into uncharted waters.
> Check online forums (as always, Google is your friend) to see if anyone
> else has installed the same OS and what (if anything) they had to do
> special.
>
> If installing something common (Windows XP or higher, Linux with a 2.6
> kernel), you'll probably have no trouble. Read the documentation
> though--you might have to install a small tools package into the guest
> OS so that it performs better.
>
> >How do you start a VM with a guest OS?
>
> In VirtualBox, you launch the VirtualBox application, then select which
> VM you want to run, and click the start button for that VM. Other
> desktop VM architectures are probably similar. In other words: easy.
>
> >How do you run multiple guests of the same OS?
>
> Create multiple VMs. (If virtualizing an OS that is somewhat piggish in
> its use of resources *Windows* *cough* *cough* then plan on having lots
> of free disk space to create the VMs and lots of RAM if you want to run
> more than one at a time.)
>
> >How do you run multiple guests of different OSs?
>
> Create multiple VMs.
>
> >How do you divide up the disk space for the different guests?
>
> However you want. When you create a VM, you'll be asked how much disk to
> allocate to it. In your host OS the VM's disk will appear either as a
> single large file, or a few smaller files of some small number of GB
> each.
>
> >Can the VM run off the C drive and guest 1 think that the D drive is
> >its C and guest 2 think that the E drive is its C?
>
> >Can the C drive be partitioned and a different partition given to each
> >guest as its C drive?
>
> OK, now we know that you're planning on running Windows as the host OS.
>
> Unless i'm misunderstanding, these 2 are the same question, just phrased
> slightly differently. So i'll answer both at once:
>
> This should be possible (depending on which VM architecture you choose),
> but generally is considered a very advanced way to set things up.
> Normally, each VM's disk is just a file on the host OS, not a partition.
> If you don't have enough space on C: for your VM disks, you should be
> able to put them somewhere else. Non-Windows VMs usually only need a few
> GB disk space.
>
> >How can files be shared between guests if needed?
>
> Most VM architectures allow you to mount part of the host filesystem as
> a network drive. Usually you have to install some small tools first, but
> it is all pretty easy to setup. If the VM software doesn't make it easy,
> you could use whatever file sharing the guests support: NFS, CIFS, etc.
>
> >How do you switch the video and keyboard between guests or do you need
> >to have one for each guest? If so, how do you connect multiple videos
> >and keyboards to a computer?
>
> On desktop virtualization, the guest appears in a window on your
> desktop. To switch to it, you either just move the mouse over it, or (at
> worst) have to click in the window.
>
> >How do you maintain the VM? Install patches, update apps, etc.
>
> Do you mean the VM software itself? Same as any other software. You
> either apply updates when they come out. Or you don't. Up to you. If
> you're guest OS is something that has proper package management (such as
> most Linuxes), then you don't have to worry about it--the package
> manager will apply updates when/if they are available.
>
> >How do you maintain the guest OSs?
>
> Same as you do when they are running on bare hardware.
>
> >How do I let the system know that the USB device plugged into that
> >port needs to be connected to guest X?
>
> The VM software should provide a way to do this. If that is important to
> you, look for that feature when choosing which VM software to go with. I
> know the non-Free version of VirtualBox will do this, and it is free.
>
> >Can I switch a USB port between guests as necessary, or once it's
> >assigned is it stuck, until I reboot, forever, etc. ?
>
> You should be able to switch.
>
> >Are there any special considerations for living in the country and only
> >having dial up access?
>
> Setting up networking on the VMs might be more interesting, but
> basically, no.
>
> >And then there is the ultimate question, what don't I know about VMs
> >that I should know?
>
> I'd suggest downloading and installing some VM software. Then install a
> guest OS or two (or three). Play with the software. Read the
> documentation. Those are the best ways to get used to the concepts of
> how it all works.
>
> >Or is there a book that I should be reading instead of tying up
> >meeting time?
>
> I haven't read any dead-tree books on virtualization. But most of the
> software comes with detailed PDF documentation. Reading some of that
> will help your understanding.
> __
> Daniel A. Ramaley
> Network Engineer 2
>
> Dial Center 118, Drake University
> 2407 Carpenter Ave / Des Moines IA 50311 USA
> Tel: +1 515 271-4540
> Fax: +1 515 271-1938
> E-mail: daniel.ramaley at drake.edu
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