Issues running our custom-made VMs

Hello everybody,

Now it's time to talk about the issues that we have found while trying to use our own VMs on Eucalyptus rather than those pre-packed ones.

Basically the VMs worked, but not as smooth as the certified images. I'm just saying that, because we don't know yet why we had some problems, using our root filesystem with the pair kernel/ramdisk provided by them.

One issue is regarding the DHCP. When we tried to boot the VM with the kernel and ramdisk provided by the pre-packed images, the dhcp doesn't work. The system shows this msg: socket: Address family not supported by protocol - make sure CONFIG_PACKET (Packet socket) and CONFIG_FILTER (Socket Filtering) are enabled in your kernelconfiguration!

However, if we just select a manual IP in the linux configuration, then the boot works fine. The problem in this case is that Eucalyptus never realizes that the VM has an IP, and that is a problem in a cloud environment, assuming that everything should be automatic.

The same problem happened with the Debian image. We therefore suspect that something other than a normal system installation is required. We are trying to get some information from the Eucalyptus forums, but at this point we are stuck in this step. At least it worked, but not as well as we expected.

Another issue that we didn't figure out yet is related to the Xen hypervisor. When we try to boot our rootfs using the pair kernel/ramdisk mentioned before, we need to explicitly specify an extra configuration into the Xen setup file. Otherwise, after loading everything, the system stops and does not show the login prompt.

It took some time for us to realize what was happening. At the beginning we thought that the VMs were not working, since we didn't have their IPs (due to the previously mentioned problem) and we couldn't log into the VMs. Below is the line that we had to add to our Xen configuration file.

extra = 'xencons=tty console=tty1 console=hvc0'

Our assessment at this point is that using a pre-packed image works better and with less headache than trying to create our own image from scratch. However, it shouldn't be so hard to use a custom VM. Maybe it is something related to Xen...

For this reason we are now thinking in doing some extreme modifications in our academic cloud. Keep reading to see what happens.

Until next post.

Lucio