Creating Fusion Drive incorrectly with HDD before SDD?

I have created a fusion drive using a 128GB SSD and a 4TB HDD. Disk Utility originally formatted my 4TB HDD as a CoreStorage volume, I had to 'delete' the coreStorage, and then 'create' a Logical Volume Group (LVG). Once I did that, I 'createVolume' the whole CoreStorage volume (LVG). I thought it was pretty cool actually that everything worked as expected!

I have read a few articles explaining how it works and some ideas, one such article said that CoreStorage automatically detects the SSD and uses that first as it should.

However, when I ran 'iostat -d disk0 disk1' terminal command to see what physical drives were in use, only my 4TB HDD appeared to be in use.

I then typed 'diskutil cs list' (output below). That command will list only the coreStorage (cs) information and I noticed that the two physical drives listed as "Index: 0" and Index: 1" starting with the HDD. I wanted to confirm that the first Index drive is supposed to be the SSD and that CoreStorage knows nothing about which physical volume is actually the SSD and which is the HDD.

Is it true that for a fusion drive to work properly the SSD should be the first indexed physical drive in the CoreStorage logical volume group? (Otherwise, my iMac is treating my 4TB HDD as the fast SSD and vise versa)

I can spend another half day and start from scratch by typing:
instead of what I actually typed:

Would I be wasting my time redoing my Fusion Drive, or would retyping the correct command fix the problem of my HDD doing all the work and my SSD unused (for the first 3.9TB)?

I get the following output when I look at my coreStorage list:


Please refer to this identical thread in it's more appropriate category:https://forums.macrumors.com/showthread.php?p=19524698#post19524698