Disk numbers in Disk Management matters?

I'm so glad this old thread is still here. It shows that what I am seeing is normal in its abnormality. I'm still happily using Windows 7 years after it passed into non-support. It still works just fine.

I had a W7 system with 2 hard drives. They were always numbered 0 & 1. They weren't particularly large drives.

I added 2 6T drives because, of course, that's the way of computers. You run out of disk space. They were consistently numbered 2 & 3. The numbering never changed.

A couple of years passed & tell me you're surprised, I decided I needed more disk space. So I added 2 18T drives. You'd think they would be numbered 4 & 5. You would be wrong. They became 2 & 3. The ones that were originally 2 & 3 became 4 & 5. This stayed like this pretty consistently.

But it bugged me. I had the 2 18T drives connected to connectors that were labeled 4 & 5 on the motherboard. But they kept coming up in Disk Management as 2 & 3. I thought it might be because of the drive lettering. I formatted the 6T drives as single partitions & gave them letters M & N. When I got the 2 18T drives, I formatted them as well as single partitions & gave them letters I & J. So I & J are alphabetically before M & N. I assumed this made the disk numbering go the way it went.

Thing is, I've got partitions with letters C, E, G, H, K, L, & Q scattered across the 2 original drives & not in alphabetical order. So my theory about the system keeping the drives in alphabetical order by drive letter is just made up & immediately disproven.

On multiple occasions, I spent a few hours swapping the data cables around on the 6 hard drives. This involved multiple shut downs/power offs, of course. I'm crazy but I'm not dumb. I never could get Disk Management to number them corresponding to the labels printed on the motherboard. I did see odd things in the Resource Monitor on the Disk tab showing drive letters like S:3, S:7, weird junk like that. For a time, Resource Monitor didn't even list all 6 drives. In the body of the tab, in the Disk Activity pane, all my drive letters would appear. But in the bottom of the window, in the Storage pane, it listed only 4 of my drives. When this was going on, Disk Management still listed all 6 drives . . . always in what I considered to be the wrong order.

I finally got fed up with the whole thing earlier today & very carefully recabled all 6 drives in numerical order according to the labels on the connectors on the motherboard. The weird S:3, S:7 junk is now gone. Resource Monitor refers to files using their correct drive letters & shows letters on all 6 drives. But the order of the drive numbering is still out of whack with the labeling on the motherboard.

Here's where it gets completely crazy. Shortly after I booted up, I looked in Disk Management & saw the numbering I kind of expected to see. Disks 0 & 1 were as I expected. Disks I & J were 2 & 3. Disks M & N were 4 & 5. But now, a couple of hours after my most recent boot up, Disk Management is showing this:

Disk 0 is I, Disk 1 is J, Disk 2 is C & a couple of others (this has always been Disk 0), Disk 3 is K & a couple of others (this disk has always been Disk 1), Disk 4 is M, Disk 5 is N.

In other words, since I booted up, there have been at least 2 configurations in place for my disk numbers. I can only imagine what I'll see tomorrow.

Somebody put a reference above to a post in another thread authored by somebody under the name Dwarf. His explanation makes as much sense as any. It's certainly deeper than I've ever gotten into it.

But how does my system run? Perfectly. As ever. Time to just throw my hands up & walk away. I was going to give up on this anyway but I decided I'd check in here on the off chance I'd get some advice on how to change things. Instead, I've found out I should just leave well enough alone. Thanks to all who participated in this thread . . . OVER TEN YEARS AGO!!!!

- - - Updated - - -

Words are always nice but sometimes pictures tell so much more. So here I've taken a couple of pictures. I did this by opening 2 instantiations of Computer Management. It was the only way I could think of to open the items I needed to show side by side. For example, for the information on a given disk, I wanted to show what was on both the General tab & the Volumes tab. But I can't open the Device Properties dialog twice from the same instantiation of Computer Management in the Device Manager function. Similarly, in order to show the full mapping of my partitions in the Disk Management function, I needed to use 2 instantiations of Computer Management. These images take advantage of both my monitors. You will probably have to magnify the images to actually understand what's in them.

I've highlighted some of the Location information for one hard drive. Every hard drive shows that it's at Location 0, Target 0, Lun 0. I'm guessing Lun means logical unit number. The only thing that's different about the Locations is the Channel number. These numbers indicate the actual port numbers of the SATA interfaces printed on my motherboard. This proves that I do indeed have the data cable for each drive attached to the SATA interface I claim it's attached to. But the Disk Numbers selected by Windows are scrambled from that order. Also, what Disk Management shows now, which is what I'm showing in the second attached image, is not what I saw shortly after I booted up yesterday. (I have not rebooted since then.)

The only curiosity is the 2 small system partitions. On my boot drive, it has the label system (all lower case) & no drive letter. If I understand things correctly, this is a special bootloader partition created by the Windows installer. On my other legacy drive, there is another such partition, but here it's got the label system (again all lower case) & drive letter S has been assigned to it. This drive did used to be my boot drive in a past life so the system partition must have been created by a Windows install I did rather a while ago. I have never even attempted to look inside those partitions to figure out what's there. I seem to be no worse off for this ignorance.

I suppose if Dwarf is correct in his description, that the order of disk numbers reflects the relative speed of each device to respond to the request for enumeration, then the order of my Disk Numbers reflects the speed of my devices. My two 18T drives came back first, then my 2 small legacy drives, & finally my two 6T drives. But this response order occurred rather a while after I booted. Shortly after I booted the order was this: my 2 small legacy drives, then my two 18T drives, & finally my two 6T drives. At boot time, Windows numbered the drives one way, then later decided to shuffle the numbering. I suppose in the end, the only important thing is whether the system runs properly. Like I said before, mine does. Everything is normal. I consider that I have contemplated my navel quite enough on this subject now.

@WildWilly

Disk drive numbers may not correspond to the SATA channel numbers when you install Windows on a computer that has multiple SATA or RAID disks

drives are enumerated in the order in which they are presented to the operating system through Plug and Play.

Therefore, hard disks may have different disk numbers across multiple system startups.

Disk drive numbers may not correspond to the SATA channel numbers when you install Windows on a computer that has multiple SATA or RAID disks