On 08/28/12 13:55, Andreas Davour wrote: Hi Andreas, The <memory> directive contains the maximum amount of memory you are giving to the guest. While the guest machine is running you can only change the allocation for the guest using the memballoon driver, but you can't increase it beyond what's set in <memory>. Please note that decreasing the amount for a guest works only if the memballoon driver is loaded in the guest. While the machine is booting the guest has access to all memory specified in <memory> so you might run low on memory when you try to start such guests in parallel. (Memory amount allocated to the guest using memballoon is stored in element <currentMemory>) With this you might use this in a scenario, where you have multiple guests, but the guests only need large amounts of memory for short time and not at the same time. You can then specify that together the machines exceed memory of the host, but you return the memory to the host using the memballoon driver and assign it back only if you require it. Peter