How to match an Windows (HyperV) disk to a SAN attached disk using the wwn

Where do I find the wwn of a disk in Windows / HyperV? That’s the question.

There are a number of identifiers to find out which LUN is which disk, but the only undeniably unique number to find out which disk is which LUN is by using the globally unique wwn number of a LUN. The question is: “where can I find the wwn of a disk in HyperV?”

The LUN number, as assigned by the storage array can be found by using diskpart:

PS C:\Users\administrator> diskpart

Microsoft DiskPart version 6.3.9600

Copyright (C) 1999-2013 Microsoft Corporation.
On computer: SERVER01

DISKPART> lis dis

Disk ### Status Size Free Dyn Gpt
——– ————- ——- ——- — —
Disk 0 Online 278 GB 0 B
Disk 1 Online 60 GB 0 B
Disk 2 Reserved 4096 GB 0 B *
Disk 3 Reserved 2048 GB 0 B *
Disk 4 Reserved 1400 GB 0 B *
Disk 5 Reserved 2048 GB 0 B *
Disk 6 Reserved 3272 GB 0 B *
Disk 7 Reserved 3273 GB 0 B *
Disk 8 Reserved 3072 GB 0 B *
Disk 9 Reserved 50 GB 0 B *
Disk 10 Reserved 1024 GB 0 B *


Disk 109 Reserved 4096 GB 0 B *
Disk 110 Reserved 4096 GB 0 B *
Disk 111 Reserved 3584 GB 0 B *
Disk 113 Reserved 3584 GB 0 B *
Disk 114 Reserved 3072 GB 0 B *

DISKPART> sel dis 80

Disk 80 is now the selected disk.

DISKPART> det disk

DGC VRAID Multi-Path Disk Device
Disk ID: {EF84EB46-E04A-4598-B101-24513B2B8784}
Type : FIBRE
Status : Reserved
Path : 0
Target : 17
LUN ID : 22
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 : Yes

There are no volumes.

DISKPART>

The highlighted line is the Host LUN id.

But to get to the wwn you need one more step. Suppose you need to know what wwn the “DR test” disk has in this screenshot:

So on host “host 1” this disk has disk number 18. The name of the mountpath is “Volume1”.

Now open a command prompt on “host 1” and start “diskpart”.

  • list disk
  • select disk 18
  • detail disk

As you can see, the LUN id is listed, but the volume name “Volume1” and its size also match what is displayed in the Failover Cluster Manager. But to be 100% sure, we need to list the wwn.

So the “diskpart” disk 18 is the one we need. Now exit “diskpart” and perform an “mpclaim -s -d”. Especially the “mpclaim” command is a little vague, since it shows 2 columns of disk numbers.

The highlighted line represents the disk we need the information (wwn) of. But now it get easy:

Perform the command “mpclaim -s -d 17” to list the details of this disk. We need to take the left column of disk numbers here, so make sure you make the right translation. The right column is what you see in diskpart and the left column is the one we need.

The highlighted serial number is the wwn we are looking for.

Now compare this wwn to the wwn you can see on your storage system and if it’s the same one, you know which LUN matches the disk on this cluster.

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