SS2k5 EE: SAN, Allocation Units, And All That Jazz

I've been doing some testing on the SAN/Disk subsystem over the past few days. I've run into something that is bugging me though. Hopefully someone here has run into the same thing or can answer.

*All LUNs have been created with default selects.

Test 1:
LUN1 (H:) - Created partition with diskmanager in win2003.
LUN2 (I:) - Created partition with diskpart and aligned the sectors at 64k.
Formatted both disks to have 4k in the allocation units.
Created a new blank DB on each disk.
With Profiler running, I ran a bulk insert for both disks and also ran a "Select count(*), Sum(total) from tableA" for both databases and cleared the proc cache inbetween.
Profiler showed the reads and writes io for the import and selects as a the same number (468721 reads and 312182 writes).

Test 2:
Deleted partitions
LUN1 (H:) - Created partition with diskmanager in win2003.
LUN2 (I:) - Created partition with diskpart and aligned the sectors at 64k.
Formatted both disks to have 8k in the allocation units.
Created a new blank DB on each disk.
With Profiler running, I ran a bulk insert for both disks and also ran a "Select count(*), Sum(total) from tableA" for both databases and cleared the proc cache inbetween.
Profiler showed the reads and writes io for the import and selects as a the same number (468721 reads and 312182 writes).

Test 3:
Same as test 2 but formatted with 64k allocation units.


So here is my question: Shouldn't the I/O go down or at least change if you change the allocation unit size for the disk?


Thanks,
Daniel