Comment #2 on issue 124 by carlos.m.rodriguez: starting up more than one instance inside the same node gives a Xen Error.
http://code.google.com/p/ganeti/issues/detail?id=124
This is how I debugged the problem. The vm config files that ganeti creates are inside /etc/xen/somehost.yourdomain Those files specifies the drbd disks as: disk = ['phy:/var/run/ganeti/instance-disks/somehost.yourdomain:0,hda,w'] /var/run/ganeti/instance-disks/somehost.yourdomain:0 is a symbolic link that points to the real drbd resource for example /dev/drbd0 The number at the last part of the disk ( :0 ) definition is the problem. Because there is a parsing issue somewhere (don't know if ganeti or XEN) that tells XEN that de disk is :0 instead of the full string. So when you start more than one instance with the :0 at the last part of the definition, XEN believes that the disk is already used and refuses to start more than one instance. I changed the symbolic link by dropping the number and make the change accordingly in the XEN config for that VM. That change allowed me to start-up more than one instance. I did this modifying the files directly and starting them with xm create. However, it defeats the purpose of having ganeti, because you'll end up managing instances components individually. My guess is that the XEN hypervisor on CentOS uses ':' colon for parsing when validating the VM config to eliminate split-brain. However I didn't look for the code nor submitted a patch. I did solve the issue changing the distribution altogether. Carlos Rodriguez
