Virtual machines@IBR

Why virtualization?

Sometimes it is desirable to have machine just for you. Whether you need root access that you won't get on the official machines or that you need to work in a different environment in contrast to the environment our admins currently provide. However, most applications do not need the full CPU, disc and memory capacity and performance of a dedicated machine. With virtual machines, seperate machines can be set up on the same physical host. Usually, you don't see the difference between a physical host and a virtual one.

Furthermore, virtual hosts are quite easy to set up. They offer copy-on-write filesystems that can restore a predefined state at any time. We currently use virtual host for software testing, as servers for security related or otherwise dangerous services, for practical courses which require root access for students, for creating larger test setups with 3 or more machines on different networks, and for several other purposes.

How can I get a machine?

You can request new virtual hosts and manage your existing ones via our Virtual Host Manager (VHM). This service is restricted to staff members only. However, you can give students operator rights to boot or shutdown specific machines.

Hardware

Currently, we have two servers which are hosting virtual machines. The first is skynet.ibr.cs.tu-bs.de, a 4HE PC, dual Xeon 2.8 GHz w/ 2 GByte RAM, that runs User Mode Linux virtual machines. The second one ist animator.ibr.cs.tu-bs.de, an IBM x336 server, dual Xeon 3.2 GHz w/ 8 GByte RAM, that runs currently Xen virtual domains. As of early 2006, Animator hosts all active virtual machines. In the near future, skynet will become a Xen test server thus switching completely from UML to Xen.

Known Bugs

How do I ...

... get my own virtual machine?

First of all, you have to be a PhD student or a staff member to be eligible for your own virtual machine. If you believe your work can benefit from a virtual machine and you are a graduate or undergraduate student, please talk to your supervisor. He can get you your own machine.

New virtual hosts can be requested via the IBR Virtual Host Manager (VHM) web interface. For the moment, virtual host setup is done in semi-automatic way which means that someone has to adjust a few knobs manually here and there before your new machine can actually boot up. You'll get an email as soon as your new machine is ready. Besides the inital setup, all other changes can be done by yourself. All new virtual machine owners should also read the "What else is important to know?" section below.

... can I access my virtual machine?

You can access the console of your virtual machine by logging in on animator.ibr.cs.tu-bs.de with your IBR username and password. If you are at the console of your virtual machine, you should be able to login with the credentials given to you in the host setup mail. Of course, you can install your own SSH/WWW/... server on your virtual machine if you like. Please note that you have to install and configure SSH service on the virtual machine by yourself before you will be able to login directly to your machine over the network.

... give my student access to my virtual machine?

If you are running your own SSH/WWW/... server on your virtual machine, you can create users and set passwords as you would normally do on any other real computer. In order to be able to boot or shutdown the virtual machine via the Virtual Host Manager (VHM) web interface, you have to add your student to the list of operators for your virtual machines. Operators can boot or shutdown virtual machines as well as get access to the console of your machine. However, they are not allowed to change any of your host settings (name, RAM, disk, network, etc.)

... boot/shutdown/restart my virtual machine?

You can use the Virtual Host Manager (VHM) web interface to change RAM sizes for your virtual machines. Just click on the name of your machine in the menu on the left side of your browser and the press the button below your host configuration table. There will be a "Boot" button for machines that are currently shutdown or a "Shutdown" button for machines that are currently running.

... get more RAM for my virtual machine?

You can use the Virtual Host Manager (VHM) web interface to change RAM sizes for your virtual machines. You have to shutdown/reboot your virtual machine via the web interface in order for the changes to take effect. A simple reboot from inside your machine is not enough for this.

... get more disk space for my virtual machine?

For the moment, the VHM web interfaces does not support adding, removing, or resizing of disks. Please email Dr. Oliver Wellnitz with your wishes.

... re-wire my virtual machine to a different network/... add or remove network interfaces??

For the moment, the VHM web interfaces does not support changing network settings. Please email Dr. Oliver Wellnitz with your wishes. For larger setups, please include a network map.

... get my questions answered that are not covered here?

Please ask Dr. Oliver Wellnitz.

What else is important to know?

Firstly, it is important to point out that your own virtual machine comes with a lot of liberties and responsibilities. So here are some points which are important to know:

• This is my machine. There are many like this, but this is mine.
  Yes, it is. But this also means that you have to deal with all nits and bits of system administration starting with the setup of network settings, IP addresses, installation of programs, backup, and so on. However, we are happy to help if you run into problems that cannot be solved by reading manual pages.
• Disable Thread Local Storage (TLS) libraries.
  If you experience problems with some of your programs, please make sure that you don't use Thread Local Storage (TLS) libraries for your programm. You can check your program with ldd(1). The reason behind this is that our used virtualization mechanism don't get along well with TLS. Usually, all you need to do is to mv /lib/tls /lib/tls.DISABLED. And please remember to check this after you installed software updates to your machines.
• Keep your machines up-to-date.
  It's a hostile network out there. Bad people are doing bad things and we already had several breakins into our virtual machines. So please, exercise common sense and update your software regularly.
• Backup your data.
  You should take care that important data on your machines is properly backed up someplace safe. Don't expect anybody to do it for you. While we store all virtual machines on RAID-1s, even two disks can fail at the same time. It's better to be safe than sorry.

Admin Stuff

This section probably only interesting for the IBR technical staff but feel free to read on. TBD.