In a malicious attempt to bring the world to an end, I began hatching a plan to use up all GUIDs.
If we assume that GUIDs are simply 128-bit numbers (usually seen by human eyes in a hexadecimal representation), then to use them all, we simply need to use all integers up to 2128. The word ‘use’ here needs defining. If a number is represented with a CPU for a few microseconds, while being a loop counter, I think that doesn’t count as using it. What really needs to happen is that each number’s representation is stored somewhere.
How could GUIDs be stored? Storage size could be a problem. Each GUID needs 16 bytes of storage; a terabyte of storage can hold 236 GUIDs. So we need 292 terabytes to store all GUIDs. If we could make terabyte hard disks the size of a grain of sand, and we replaced every grain of sand on every beach on Earth with such a hard drive, we’d need 500 million Earths to store all GUIDs.
I’ve probably got my sums wrong here, but even if I’m out by several powers of ten, I think the range of GUIDs is enough for now.