We hope that you're enjoying using SIPB Virtual Servers. We've been working
hard on making it better recently, and we have a few new features that you
might like to know about. Also, we have a few recommendations and requests to
help keep the service usable.

1. Please turn off your VMs when they are not in use.
We don't want to discourage people from using SIPB Virtual Servers as an easy
way to create machines to handle tasks. However, our capacity to run VMs is
finite. If you have a VM that is powered on but not doing anything, we
encourage you to power it off.

2. Please don't leave a VM in a kernel panic or sitting at the boot prompt.
Kernel panics or boot prompts on install CDs use all of the CPU at their
disposal - they "spin." Due to flaws in the virtual machine host that we have
yet to resolve, this severely and negatively impacts the performance of all
other VMs.

3. Try the sipb-xen-console server
All VMs have a serial console interface connected to them, and we have exposed
this through the console server, sipb-xen-console.mit.edu. If you're using
Debian or Ubuntu, there are excellent instructions at
https://help.ubuntu.com/community/SerialConsoleHowto for enabling use of the
serial console.

Once you've configured the console, you can ssh into
<machine-name>@sipb-xen-console.mit.edu using your Kerberos tickets to attach
to the serial console. If you're using an Athena machine, you should just be able to run:

athena% ssh MACHINE-NAME@sipb-xen-console.mit.edu

4. Consider migrating to ParaVM
We recently added an option to convert a hardware-assisted VM to a
paravirtualized VM. ParaVMs have better disk I/O performance compared to HVMs.
Additionally, ParaVMs shouldn't suffer from the clock sync problems that many
HVMs have been experiencing.

There is now a new set of radio buttons on the Settings portion of the Info
page for a VM. While this will make the necessary change in our database, it
is up to you to reconfigure your VM to boot into a paravirtualized kernel.
We're still ironing out the bugs, so there are a few guidelines:

- Install a Xen-enabled 64-bit kernel
  Your machine must have been installed as a 64-bit machine. If you installed
  a 32-bit machine, it is possible but very non-trivial to convert it, as it
  is currently not possible for us to boot 32-bit guest kernels.
  
  On a Debain system, installing the following packages should be sufficient
  to get a paravirtualization-capable machine:
  linux-image-xen-amd64
  linux-modules-xen-686
  linux-headers-xen
  
  To convert an Ubuntu system, installing the following packages should be
  sufficient:
  linux-image-xen
  linux-restricted-modules-2.6.22-14-xen
  linux-headers-xen
  
- DHCP does not work with ParaVMs
  We're currently investigating the issue, but for the time being you should
  configure your VM to use its static IP address. To do this on a Debian-based
  system, edit /etc/network/interfaces and change the line that looks like
  
  iface eth0 inet dhcp
  
  to read
  
  iface eth0 inet static
  address <your static IP address>
  netmask 255.255.0.0
  gateway 18.181.0.1

- The kernel must be the default in GRUB's menu.lst file
  The update-grub script on Debian systems does not add Xen kernels to the
  menu.lst file unless the machine is currently running as a Xen guest.
  
  To change this, apply the patch at
  https://sipb-xen-dev.mit.edu/trac/attachment/ticket/64/update-grub.diff to
  /usr/sbin/update-grub and run update-grub again. The Xen kernel should show
  up at the top of the list. You should make sure it's set as the default.

- Enable the serial console
  ParaVMs do not have the same VNC console access that HVMs do, so you will
  have to access the VM through the serial console. If you have not configured
  the serial console (see the instructions above), it will not be possible to
  access the device directly to diagnose problems.

Once you have completed all of these steps, you should be able to shutdown the
VM, change it to ParaVM mode, and boot it up again. Remember that you can't
access the VNC console of a ParaVM like you can for HVM, so you'll need to
control it through the sipb-xen-console server.

Please feel free to contact us with questions, comments, suggestions, or
problems regarding SIPB Virtual Servers,

- The SIPB Virtual Servers Maintainers