XEN with loopback devices
One of the most annoying things with [stag]XEN[/stag] and [stag]loopback[/stag] devices is that at some point you will run out of them. Especially if you like me have a setup with more than 15 virtual servers (not all of them are running at the same time). I just ran into "Error: Device 5632 (vdb) coulnt not be connected. losetup $lo flags $loopdev $file", which after some digging means that there are no free loopback devices. The nice thing is that there is a way to solve it, instead of having; In your [stag]DomU[/stag] replace disk=[ ..., 'file:/..../file.iso... with disk=[ ..., 'tap:aio:/..../file.iso... Then you DomU should start just fine. Read more here .