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Windows 7: SATA port numbers vs assignemnt of Disk numbers/

26 Oct 2011   #1

DELL Win 7 Home Premium 64 Bit
SATA port numbers vs assignemnt of Disk numbers/

I have three SATA hard drives :
  • Main system/boot drive , WD Caviar Black 1 TB, connected to the SATA 0 port
  • A backup drive, identical WD Caviar Black 1 TB, connected to the SATA 1 port
  • Another dirve, Hitachi 1 TB, connected to the SATA 2 port
When I installed Win 7, only the main drive was connected... and it remains the only drive with active/system/boot partitions.

All three drives reporr correctly in the BIOS, and in the right order, but why is it that only one of the drive (the one on SATA port 1) has a "SATA:" prefix and the others have a "HDD:" prefix ?

Why is it that the assignment of Disk #0, 1, 2 ( as seen in Disk Maanger or DiskPart) does not seem to have nay rhyme or reason?

I would have expected:

- the hardrive connected to SATA port O, to be assigned as Disk 0
- the hardrive connected to SATA port 1, to be assigned as Disk 1
- the hardrive connected to SATA port 2, to be assigned as Disk 2

but instead, I have:

- the hardrive connected to SATA port 2, is assigned as Disk 0
- the hardrive connected to SATA port 0, is assigned as Disk 1
- the hardrive connected to SATA port 1, is assigned as Disk 2

Just curious why that is.

I am assuming there is no way to chagne this. Its not something I would dream of reinstalling Windows 7 to correct ( even if it did correct it).

Attached Thumbnails
-sata-q-list.png   -sata-q-ports.png   -sata-q-dm.png  
My System SpecsSystem Spec
26 Oct 2011   #2
Microsoft MVP

Win 7 Ultimate x64

Best advice, leave it alone. It may bother your (and others) sense of order but it won't affect how anything works, and no re-installing Windows won't change it.
My System SpecsSystem Spec
11 Dec 2011   #3

Windows 7 Pro 64bit
SATA ports, Disk numbers, and Windows Setup

I realize this thread's old, and the single response suggests it's not something many people have noticed or care about. But.....

I've always assumed, supported by the evidence of my particular Windows machines, that:
  1. SATA port numbers reflect physical locations, i.e., connectors on the M/B. Iin the BIOS, these have labels like P0, P1, etc.
  2. These SATA port numbers translate directly to the disk numbers shown in Windows Disk Management.
  3. Windows Setup uses these same port/disk number assignments in its partition selection display.

So in a two-drive laptop, the hard drive in the P0 bay becomes Windows Disk 0, and if you re-install Windows, that drive's partitions will be displayed as Disk 0 Partition 1, Disk 0, Partition 2, etc.

Recently, however, I've seen two cases that proved my #3 assumption wrong. The BIOS, Diskpart, and Windows Disk Management all show the disks consistently. But then Windows Setup reverses the disk numbers.

Can anyone explain how Windows Setup constructs that disk/partition table? And what could be happening to reverse the disk numbers like that? If an owner relied on the disk numbers they see in Disk Management to select their new install location, this reversal in Windows Setup could be disastrous.
My System SpecsSystem Spec

11 Dec 2011   #4

Windows 7x64 Home Premium SP1

Quote   Quote: Originally Posted by BrodyBoy View Post
I realize this thread's old, and the single response suggests it's not something many people have noticed or care about.
I wouldn't say people aren't interested. I think it's more a case of no definite answer.
My best bet goes to one of the Moderator's (Dwarf) suggestion.
Diskpart / Disk Management vs the BIOS
My System SpecsSystem Spec
11 Dec 2011   #5


I also thought of Dwarf's theory when I read the revival of this thread because it is the most logical theory I've read on this. Good on you Michael for finding it. Bookmarked.
My System SpecsSystem Spec
11 Dec 2011   #6

Windows 7 Pro 64bit

Thanks for the responses, guys. I didn't find that thread when I started researching this.....I'm off to read it now.
My System SpecsSystem Spec
11 Dec 2011   #7

Windows 7 Pro 64bit

Just finished reading the referenced thread and associated links. Really interesting stuff!

At one point, you had asked what consequence this might have, aside from being a nuisance. I see this as a serious trap for newbies trying to do clean installs, in a couple ways.
  • First, if they look in Windows to determine where to put the new install, it's very possible they could end up installing on the wrong hard drive and maybe even lose important data in the process, if the enumeration changes when they boot to the installer.
  • Second...and I didn't even know about this until I read the MS KB some scenarios, the reversed disk enumeration can cause Windows Setup to put the System Reserved partition on a different HDD from the system partition. This could cause issues down the line with drive upgrades, disk imaging, etc. This seems like much more than a nuisance, and something worth avoiding.
I frequently help the technically-challenged through clean installs, via email, PMs, or texts. If I can't figure out a way to ensure consistent drive enumeration, I can't standardize a simple instruction for determining installation location. (I'm talking about people who are completely new to this, the ones who need a step-by-step walkthrough.) I've wanted to avoid making them open their laptops to disconnect cables or remove drives, if possible.

It's clear that some folks much more knowledgeable than me have put a lot of effort into figuring this out. Nonetheless, I think I'll do some experimenting with my machines, if just to try and discern a pattern for when it happens. Intuitively, it just doesn't make sense to me that NOTHING changes between boot A and boot B, yet the disc enumeration changes.

I'm not especially optimistic that I'll find anything, considering the efforts already applied by others, but I'll report back if I do.
My System SpecsSystem Spec
11 Dec 2011   #9

Windows 7 Pro 64bit

That's the mentioned KB article. Am I missing a point you're making about it?
My System SpecsSystem Spec
09 Mar 2013   #10

Windows 7 Ultimate

I recognize that this post is literally 2 years old. However, what people have not considered is when you have an issue with windows and need to do a repair or fresh install. In my case windows in repair mode cannot find the windows drive, now this can be due to to AHCI on my gigabyte x58-ud5 rev 2 or some other reason. In my case what I needed to do was take out all of my other hard drives and load it with just windows.

If I did otherwise windows would not be seen in repair mode, then if I did a reinstall (custom) with windows 7 I had to direct it to disk 5 when in reality it was on port 0.

I wish there was an easier solutiom
My System SpecsSystem Spec

 SATA port numbers vs assignemnt of Disk numbers/

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