Which drive is \Device\Harddisk1\DR1?

Run the following PowerShell command as Administrator:

Get-PhysicalDisk | Select -Prop DeviceId,FriendlyName,SerialNumber

This will show output like:

DeviceId FriendlyName              SerialNumber
-------- ------------              ------------
1        ST1000DM003-9YN162        S1D2RPMB
5        ST1000DM003-1CH162        Z1D3CPP3
2        ST1000DM003-9YN162        S1D34BYN
0        Corsair Force LS SSD      144381700001017402C2
4        WDC WD10EFRX-68PJCN0      WD-WCC4J9CC8112
3        Samsung SSD 950 PRO 256GB 0025_3853_61B0_3DD0.

The DeviceId corresponds to the N in the \Device\HardDiskN path.

This command is useful when you are using Storage Spaces, which can prevent the physical disks from appearing in the tools referenced in the other answers, like DiskPart.

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.

http://www.chrysocome.net/dd

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 <[email protected]>
This program is covered by the GPL.  See copying.txt for details
Win32 Available Volume Information
\\.\Volume{a502c160-1241-4338-a345-b76f4a973d9f}\
  link to \\?\Device\HarddiskVolume5
  fixed media
  Mounted on \\.\c:

\\.\Volume{c8a5d58a-7083-440b-a5c1-e262ca3a9d7d}\
  link to \\?\Device\HarddiskVolume6
  fixed media
  Mounted on \\.\g:

\\.\Volume{9d1b0246-5f39-4ef8-9016-ef83d03d7255}\
  link to \\?\Device\HarddiskVolume4
  fixed media
  Mounted on \\.\x:

\\.\Volume{4ca2b56b-0778-4a61-8979-6ad9fa1df45f}\
  link to \\?\Device\HarddiskVolume7
  fixed media
  Mounted on \\.\y:

\\.\Volume{d20ed74c-0607-11e4-8256-8086f2c4e4ff}\
  link to \\?\Device\HarddiskVolume8
  removeable media
  Mounted on \\.\e:

\\.\Volume{570d1087-e7b4-11e3-824c-806e6f6e6963}\
  link to \\?\Device\CdRom0
  CD-ROM
  Mounted on \\.\d:

\\.\Volume{d20edf99-0607-11e4-8256-8086f2c4e4ff}\
  link to \\?\Device\ClvtDrv0
  CD-ROM
  Mounted on \\.\s:

(This section is only present when run as admin)

NT Block Device Objects
\\?\Device\CdRom0
  size is 2147483647 bytes
\\?\Device\Harddisk0\Partition0
  link to \\?\Device\Harddisk0\DR0         <--------------------------- DR0
  Fixed hard disk media. Block size = 512
  size is 512110190592 bytes
\\?\Device\Harddisk0\Partition1
  link to \\?\Device\HarddiskVolume1
\\?\Device\Harddisk0\Partition2
  link to \\?\Device\HarddiskVolume2
  Fixed hard disk media. Block size = 512
  size is 41943040 bytes
\\?\Device\Harddisk0\Partition3
  link to \\?\Device\HarddiskVolume3
  Fixed hard disk media. Block size = 512
  size is 134217728 bytes
\\?\Device\Harddisk0\Partition4
  link to \\?\Device\HarddiskVolume4
\\?\Device\Harddisk0\Partition5
  link to \\?\Device\HarddiskVolume5
\\?\Device\Harddisk0\Partition6
  link to \\?\Device\HarddiskVolume6
\\?\Device\Harddisk0\Partition7
  link to \\?\Device\HarddiskVolume7
\\?\Device\Harddisk1\Partition0
  link to \\?\Device\Harddisk1\DR1
\\?\Device\Harddisk1\Partition1
  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

This can be found in Sysinternals WinObj tool (run as Admin):

1. open in the tree: {Device\Harddisk[N]}.

2. note volumes mapping above and then re-check in {GLOBAL??"}: sort by SymLink column and see there which \Device\HarddiskVolume[N] maps to which disk letter.