Debugging lack of resources
You'll often see messages like this:
2012-06-04 17:34:52,558 DEBUG [cloud.deploy.FirstFitPlanner]
The important thing above is: first of all it's noting that you don't have enough resources, but which resource do you not have enough of? The Type, section (highlighted in red) combined with the below table can tell you which resource you are running low on.
CAPACITY_TYPE_MEMORY = 0;
CAPACITY_TYPE_CPU = 1;
CAPACITY_TYPE_STORAGE = 2;
CAPACITY_TYPE_STORAGE_ALLOCATED = 3;
CAPACITY_TYPE_VIRTUAL_NETWORK_PUBLIC_IP = 4;
CAPACITY_TYPE_PRIVATE_IP = 5;
CAPACITY_TYPE_SECONDARY_STORAGE = 6;
CAPACITY_TYPE_VLAN = 7;
CAPACITY_TYPE_DIRECT_ATTACHED_PUBLIC_IP = 8;
CAPACITY_TYPE_LOCAL_STORAGE = 9;
(above taken from api/src/com/cloud/capacity/Capacity.java)