How to tell which disk Windows Used to Boot

Question

I m need to find a method to programmatically determine which disk drive Windows is using to boot  In other words  I need a way from Windows to determine which drive the BIOS is using to boot the whole system    Does Windows expose an interface to discover this  With how big the Windows API is  I m hoping there is something buried in there that might do the trick   Terry  p s  Just reading the first sectors of the hard disk isn t reveling anything  On my dev box I have two hard disks  and when I look at the contents of the first couple of sectors on either of the hard disks I have a standard boiler plate MBR   Edit to clarify a few things  The way I want to identify the device is with a string which will identify a physical disk drive  as opposed to a logical disk drive   Physical disk drives are of the form      PHYSICALDRIVEx  where x is a number  On the other hand  a logical drive is identified by a string of the form       x  where x is a drive letter   Edit to discuss a few of the ideas that were thrown out  Knowing which logical volume Windows used to boot doesn t help me here  Here is the reason  Assume that C  is using a mirrored RAID setup  Now  that means we have at least two physical drives  Now  I get the mapping from Logical Drive to Physical Drive and I discover that there are two physical drives used by that volume  Which one did Windows use to boot  Of course  this is assuming that the physical drive Windows used to boot is the same physical drive that contains the MBR

User · Answer

You can use WMI to figure this out   The Win32 BootConfiguration class will tell you both the logical drive and the physical device from which Windows boots   Specifically  the Caption property will tell you which device you re booting from   For example  in powershell  just type gwmi Win32 BootConfiguration to get your answer

User · Answer

You type diskpart  list disk and check disks for boot  Ex  dispart  list disk  select disk 0  detail disk  The disk with Boot volume is disk with windows installed

User · Answer

Unless C  is not the drive that windows booted from Parse the  SystemRoot  variable  it contains the location of the windows folder  i e  c  windows

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a simpler way search downloads in the start menu and click on downloads in the search results to see where it will take you the drive will be highlighted in the explorer

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You can try use simple command line  bcdedit is what you need  just run cmd as administrator and type bcdedit or bcdedit  v  this doesn t work on XP  but hope it is not an issue   Anyway for XP you can take a look into boot ini file

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Go into Control Panel System and Security Administrative Tools Launch the System Configuration tool   If you have multiple copies of Windows installed  the one you are booted with will be named such as   Windows 7  F  Windows  Windows 7  C  Windows    Current OS  Default OS

User · Answer

That depends on your definition of which disk drive Windows used to boot  I can think of 3 different answers on a standard BIOS system  who knows what an EFI system does     The drive that contains the active MBR The active partition  with NTLDR  the system partition  The partition with Windows on it  the boot partition    2 and 3 should be easy to find - I m not so sure about 1  Though you can raw disk read to find an MBR  that doesn t mean it s the BIOS boot device this time or even next time  you could have multiple disks with MBRs    You really can t even be sure that the PC was started from a hard drive - it s perfectly possible to boot Windows from a floppy  In that case  both 1 and 2 would technically be a floppy disk  though 3 would remain C  Windows   You might need to be a bit more specific in your requirements or goals

User · Answer

Try HKEY LOCAL MACHINE SYSTEM Setup SystemPartition

User · Answer

There is no boot ini on a machine with just Vista installed   How do you want to identify the drive partition  by the windows drive letter it is mapped to  eg  c    d   or by how its hardware signature  which bus  etc    For the simple case check out GetSystemDirectory

[windows] How to tell which disk Windows Used to Boot

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