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While I was trying to find out why the main disk is performing a form of unexpained "thrashing"(while there was no RAM issue), freezing up apps temporarily, I found a relevant error in the logs:

"The driver detected a controller error on \Device\Harddisk1\DR1"

and I'm trying to find which drive it is.

However, from device manager and disk management, the main disk is "0" and there are informational mentions in the logs of dr0 when I enable/disable write caching so it does recognize 0 as different from dr1.

Howevever, the computer has no other disk that I know of and if I open it up while it does have a space for it (laptop), it has no connections for a new one.

I wonder if it's a 'hidden' device of some sort or a problem with the manufacturer's blocking of connections.

In any case I'd like to find out which that device is precisely.

On device manager, DVD drive is mentioned as 'CD ROM 0" when I use 'Populate' in the Volumes tab of its properties and similarly HDD reports disk 0. I still wonder though if for some reason the dvd drive is considered as disk 1 but there's no confirmation of it anywhere. Any other devices such as USB drives etc. are shown as 2, 3, 4 etc. on drive management.

Also looking in HKEY_LOCAL_MACHINE I can only see HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi Port 0\Scsi Bus 0\Target Id 0\Logical Unit Id 0 as PhysicalDrive2 which is a bit weird now that I think of it. That location also confirms the model of the main known drive.

When changing write caching settings \Device\Harddisk0\DR0 is reported on logs (as an information of the change) so \Device\Harddisk0\DR0 is considered by the system different from \Device\Harddisk1\DR1.

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If you open the properties of a drive in device manager, the object path will be listed under "Physical Device Object name" in the details tab. – Jan 19 '13 at 11:55
Could it just be semantics and inconsistency with Microsoft naming convention for devices that is confusing you? disk 0 in some instances will be the first hard drive, while DR1 is the first hard drive in other situations. – sunk818 Dec 3 '14 at 19:57
possible duplicate of How do Windows NT-based operating systems address devices? – bwDraco May 13 at 14:44

4 Answers 4

This "dd" utility worked for me. But it must be run as administrator to include the */Harddisk/DRx mappings!

 dd --list  <--- as administrator

It provides a report that allows tracing between the various naming schemes and includes the DRn types.

The mappings is not completely obvious but if one assumes that the NT Block Device Objects are listed in order I think the correct drive can be inferred.

If you have unique drive sizes, it is simple since the report directly shows the size for each DRn.

Update 1/23/2015: Adding sample output. This system just has one physical 512GB drive with 6 partitions and a CDRom.

rawwrite dd for windows version 0.5.
Written by John Newbigin <>
This program is covered by the GPL.  See copying.txt for details
Win32 Available Volume Information
  link to \\?\Device\HarddiskVolume5
  fixed media
  Mounted on \\.\c:

  link to \\?\Device\HarddiskVolume6
  fixed media
  Mounted on \\.\g:

  link to \\?\Device\HarddiskVolume4
  fixed media
  Mounted on \\.\x:

  link to \\?\Device\HarddiskVolume7
  fixed media
  Mounted on \\.\y:

  link to \\?\Device\HarddiskVolume8
  removeable media
  Mounted on \\.\e:

  link to \\?\Device\CdRom0
  Mounted on \\.\d:

  link to \\?\Device\ClvtDrv0
  Mounted on \\.\s:

(This section is only present when run as admin)

NT Block Device Objects
  size is 2147483647 bytes
  link to \\?\Device\Harddisk0\DR0         <--------------------------- DR0
  Fixed hard disk media. Block size = 512
  size is 512110190592 bytes
  link to \\?\Device\HarddiskVolume1
  link to \\?\Device\HarddiskVolume2
  Fixed hard disk media. Block size = 512
  size is 41943040 bytes
  link to \\?\Device\HarddiskVolume3
  Fixed hard disk media. Block size = 512
  size is 134217728 bytes
  link to \\?\Device\HarddiskVolume4
  link to \\?\Device\HarddiskVolume5
  link to \\?\Device\HarddiskVolume6
  link to \\?\Device\HarddiskVolume7
  link to \\?\Device\Harddisk1\DR1
  link to \\?\Device\HarddiskVolume8

Virtual input devices
 /dev/zero   (null data)
 /dev/random (pseudo-random data)
 -           (standard input)

Virtual output devices
 -           (standard output)

Added by barlop
I will just include a pic that illustrates somewhat enter image description here

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here is a screenshot showing how it doesn't work for me Notice that diskpart gives a better answer than dd. – barlop Jan 23 at 17:54
-1 please include a paste of the output of dd --list . For me it doesn't quite show that.. dd shows \\?\Device\HarddiskVolume1 diskpart shows disk0 and disk1. dd claims HarddiskVolume1 is not mounted, and I believe it(that volume1 whatever that is isn't mounted) but then I think that means that the paging error from my event viewer \Device\Harddisk1\DR5 (which relates to one or the other mounted hard drive, my internal one or the external one, both are moutned) so the error is not related to HarddiskVolume1 dd --list is not showing the hard disk number, but the volume number. – barlop Jan 23 at 17:58
Did you see the part that says it needs to be run as admin? I will add some sample output. – crokusek Jan 23 at 18:19
+1 You're right. I've removed my downvote and made it an upvote. Great that you included sample output. I was just making a pic, I've added a link to a pic at the end. – barlop Jan 23 at 18:42
Great pic and diagram. I think you understand it better than I do at this point. – crokusek Jan 23 at 19:12

You can also do this as administrator:


    Microsoft DiskPart version 6.1.7601
    Copyright (C) 1999-2008 Microsoft Corporation.
    On computer: COMPUTERNAME

    DISKPART> list disk

      Disk ###  Status         Size     Free     Dyn  Gpt
      --------  -------------  -------  -------  ---  ---
      Disk 0    Online          476 GB    11 GB
      Disk 1    Online           59 GB      0 B

    DISKPART> sel disk 1

    Disk 1 is now the selected disk.

    DISKPART> list part

      Partition ###  Type              Size     Offset
      -------------  ----------------  -------  -------
    * Partition 1    Primary             59 GB      0 B
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I was hunting for \device\harddisk1\dr2

This will be the 2nd disk listed in diskpart:

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          476 GB  3072 KB
  Disk 1    Online         2794 GB      0 B
  Disk 2    Online         2794 GB  7168 KB
  Disk 3    Online         3726 GB  7168 KB
DISKPART> sel disk 1

Disk 1 is now the selected disk.

DISKPART> detail disk

WD My Book 1130 USB Device
Disk ID: 0002DCC8
Type   : USB
Status : Online
Path   : 0
Target : 0
LUN ID : 0
Location Path : UNAVAILABLE
Current Read-only State : No
Read-only  : No
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No
Clustered Disk  : No

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 3     H                       Partition   2794 GB  Healthy

Notice "WD My Book 1130 USB Device" and the "H" under Ltr.

\device\harddisk1\dr2 is drive H.

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In according please see:

  • HKEY_LOCAL_MACHINE\Hardware\Devicemap\Atdisk (for IDE-based devices)
  • HKEY_LOCAL_MACHINE\Hardware\Devicemap\SCSI (for Atapi-compliant or SCSI devices)
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