Diskpart / Disk Management vs the BIOS

[Bare Foot Kid]

Hello everyone.


I know some of you have seen this issue before and I'd like to get your input on this; I and some others have been working on this in this thread linked below.

http://www.sevenforums.com/performance-maintenance/178209-dont-know-why.html

Another new / clean install is connected to the #1 SATA port of the mobo and set as the first boot device and it was the only HDD connected for the clean install.

Originally the "Movies" HDD was Disk 2 after the others were reconnected but that changed also at a later time.

Edit: I just posted more in the second post down.

This time all the HDD were connected for the clean install, the "Disk #" changes at random intervals and is sometime different from one look at disk management / diskpart to another, it's completely screwy.

This first set of snips is the way it should be and is the way it is some of the time, the second set is from just a few minutes later, sometime the "Storage" HDD is Disk 0 and sometime the "Movies" HDD is disk 0, the C: should be Disk 0 the first snip is the BIOS listing.

Any ideas, anybody?

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[Bare Foot Kid]

Here see what I mean, I just now got these.

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[HammerHead]

Curious

I'm curious also. Have you tweaked the Plug and Play setting in the Bios.

 

[Bare Foot Kid]

Hello Bob.


No as a matter of fact, I reset the BIOS/CMOS to default before the first set of clean installs and the only change I've made was from IDE to AHCI, everything is at default.

Thanks for the interest.

 

[HammerHead]

Plug and Play

I have alway ran mine as "Yes". To run it as "No" I am not quite sure what you would get. I assume the bios would do the settings and Windows would have to accept them. Don't know if that is correct because I have never tried it. It might make a difference in what you are describing.

 

[mjf]

Yes and I'm waiting for some feedback on the work I did here
http://www.sevenforums.com/performance-maintenance/178209-dont-know-why-3.html#post1516432

By all means critic it but I haven't seen a better explanation so far.
I'm saying it's not sata ports but disk signature and a corresponding disk signature entry in the Registry. This was all new to Vista and Windows 7.

 

[Bare Foot Kid]

Yes and I'm waiting for some feedback on the work I did here
http://www.sevenforums.com/performance-maintenance/178209-dont-know-why-3.html#post1516432

By all means critic it but I haven't seen a better explanation so far.

Sorry about that mate, I meant to have another look and get some feedback and got sidetracked; good work BTW, I was impressed whan I saw it early this morning but I was on the way out the door.

Is there a way to get the HDD manufacturer serial/model numbers from the Registry?

I'll have another, better look after while.

 

[mjf]

Yes and I'm waiting for some feedback on the work I did here
http://www.sevenforums.com/performance-maintenance/178209-dont-know-why-3.html#post1516432

By all means critic it but I haven't seen a better explanation so far.

Sorry about that mate, I meant to have another look and get some feedback and got sidetracked; good work BTW, I was impressed whan I saw it early this morning but I was on the way out the door.

Is there a way to get the HDD manufacturer serial/model numbers from the Registry?

I'll have another, better look after while.

This is about disk signature not serial number. It is a fundamental change made in Vista and Windows 7. The explanation I gave is apparently new.

 

[Bare Foot Kid]

Yes and I'm waiting for some feedback on the work I did here
http://www.sevenforums.com/performance-maintenance/178209-dont-know-why-3.html#post1516432

By all means critic it but I haven't seen a better explanation so far.
I'm saying it's not sata ports but disk signature and a corresponding disk signature entry in the Registry. This was all new to Vista and Windows 7.

What I don' have a grip on is how the disk signature in the Registry keeps changing from one time to the next.

I just wondered if the HDDs could be differentiated in the registry using mfg information.

Thank you for all your input on this!

 

[mjf]

The Windows OS controls the management of disk signatures. It's an 8 bytes entry in the MBR just like the partition table is.
Windows generates a unique disk signature when the disk is initialized. When the first 512 bytes don't end with 0x55AA Windows does not recognize the existence of an MBR and asks you (or it) to make one by initializing the disk. If the disk is not re-initialized it will keep its old disk signature.
Then this disk signature is associated with a disk number and stored in the registry where I have shown in my snip.
http://www.sevenforums.com/performance-maintenance/178209-dont-know-why-3.html#post1516432
When Windows boots it checks each disks' disk signature (in each disks MBR) with the registry entries. If the disk signature is in the registry it gets assigned the matching disk number.

Here is a Windows generated disk signature in my boot disks MBR below and the registry entry above.


Hence you get what you've been seeing. I have not seen this explained before so I welcome criticism so I may learn.

Again this a new important role for the disk signature which didn't exist prior to Vista.

 

[Bare Foot Kid]

Hello mjf.


Here's additional info concerning your post #34 in the other thread, this is getting stranger and stranger, the "Properties, Hardware" does not even match the current disk management listings, those positions have actually changed while I was taking these snips.

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[mjf]

After more experimenting I started getting my my disk 0 bumped into disk 1 spot!
All the fiddling (including BIOS boot ordering) couldn't rectify the switch. I now doubt the importance of the registry entries. Changing the registry entries didn't fix the problem

Back to the drawing board - or maybe not.

 

[Dwarf]

I've noticed that on occasions myself, and this is my theory as to why it happens.

When you power up your system, and this is more from when you do so from a power off situation, i.e a cold boot, rather than a restart, the BIOS as part of its POST routine interrogates the hardware to ascertain what devices are attached to the system. SATA devices are enumerated as part of this procedure. The BIOS lists the SATA ports in the same order as they are labelled on the motherboard, this is to allow for easy device identification from within the BIOS setup (in other words, m/b port #1 is listed in the BIOS as port #1 and m/b port #2 as port #2, etc). However, this does not necessarily represent the order in which the devices respond to the request for their presence in the BIOS POST routine. Unlike the IDE interface, which is enumerated in a fixed order, the SATA interface is enumerated in parallel, meaning all SATA devices are questioned at the same time. The device that responds first is assigned as Channel #0, the second as Channel #1, etc. For devices of equal specification, i.e. identical drives, connected to 2 separate ports (as they must be, seeing as though a SATA port can only have a single device attached to it), sometimes one will respond to the request quicker, and sometimes the other one will.

 

[theog]

Been playing with my old Vista test Rig. Results below.



Installed a JMicron JMB36X Controller.





Are you using a JMicron Controller?

 

[mjf]

I am using a JMicron JMB36X Controller.

 

[theog]

I am using a JMicron JMB36X Controller.

Can you post a screen shot of Disk management?