SQL Server on SAN, same LUN: one logical drive vs multiple

First, let me start by saying that I did notice there are multiple similar questions to this, but neither of them is exactly what I want to ask, and not one of them has a definite answer. Second, let me confirm that I do understand, that it's recommended to use different LUNs/spindles for log/data even on SAN/virtualized environment. Now the question: IF there is just one single LUN assigned to a SQL Server virtual machine, is there a **performance** (NOT management, security, or any other) difference between following configurations: 1. *One* virtual disk file (vhd, vmdk, whatever) with *one* virtual controller with *one* logical partition in virtual OS, and tempdb/data/log in that partition 2. *One* virtual disk file with *one* virtual controller but *multiple* logical partitions/drive letters for tempdb/data/log 3. *Multiple* virtual disk files one *separate* virtual controller with *separate* partitions for tempdb/data/log So far I have heard the following answers: 1. There is *no* or *negligible* performance difference, as in the end, its still just same spindle with same IO capacity 2. There *is* a performance difference in *some* scenarios because virtual controllers have separate (virtual) IO queues and scheduling in the *guest OS* If important, let's assume the workload is very large number of threads with very small requests (so deep small queue). I would like to get this settled once and for all, so I would like to ask to stay on topic of *performance on one LUN*, and refrain from suggestions for optimizing the layout.