Getting a volume GUID

NTFSD
1

HI all,

I need to retrieve a volume GUID, i.e. the unique identifier of a
partition like ??\Volume{GUID}\

I have either the NTFS device name or the DOS device name (\DosDevices\c:).

At the moment I use a IOCTL_MOUNTMGR_QUERY_POINTS where I put the
device name (both NTFS and DOS) in the MOUNTMGR_MOUNT_POINT parameters
DeviceNameOffset and DeviceNameLength.

Then I filter the answer and save the first symbolic link that starts
with ??\Volume{.

  1. Is there an easier way to get the Volume GUID?

  2. Can I use IOCTL_MOUNTDEV_QUERY_UNIQUE_ID? I guess the ID I get is
    different from Volume GUID. Is it really unique?

  3. Can I use a DOS device name as device name parameter in
    MOUNTMGR_MOUNT_POINT? It works on Windows XP, what about other Windows?

Thank you
Francesco

2

>2) Can I use IOCTL_MOUNTDEV_QUERY_UNIQUE_ID? I guess the ID I get is

different from Volume GUID. Is it really unique?

  • Yes, unique id is different than the volume GUID. Unique id is given by
    the volume manager controlling the volume. For Basic Volumes, its disk
    signature + offset and for LDM/VXVM volumes its volume GUID
  1. Can I use a DOS device name as device name parameter in
    MOUNTMGR_MOUNT_POINT? It works on Windows XP, what about other Windows?
  • I think it works on WINDOWS 2000 platform onward.

-----Original Message-----
From: Francesco Garelli [mailto:xxxxx@acm.org]
Sent: Saturday, August 06, 2005 7:22 AM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] Getting a volume GUID

HI all,

I need to retrieve a volume GUID, i.e. the unique identifier of a
partition like ??\Volume{GUID}\

I have either the NTFS device name or the DOS device name (\DosDevices\c:).

At the moment I use a IOCTL_MOUNTMGR_QUERY_POINTS where I put the
device name (both NTFS and DOS) in the MOUNTMGR_MOUNT_POINT parameters
DeviceNameOffset and DeviceNameLength.

Then I filter the answer and save the first symbolic link that starts
with ??\Volume{.

  1. Is there an easier way to get the Volume GUID?

  2. Can I use IOCTL_MOUNTDEV_QUERY_UNIQUE_ID? I guess the ID I get is
    different from Volume GUID. Is it really unique?

  3. Can I use a DOS device name as device name parameter in
    MOUNTMGR_MOUNT_POINT? It works on Windows XP, what about other Windows?

Thank you
Francesco

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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3

Pashupati Kumar wrote in news:xxxxx@ntfsd:

>>2) Can I use IOCTL_MOUNTDEV_QUERY_UNIQUE_ID? I guess the ID I get is
>>different from Volume GUID. Is it really unique?
>
> - Yes, unique id is different than the volume GUID. Unique id is given
> by the volume manager controlling the volume. For Basic Volumes, its
> disk signature + offset and for LDM/VXVM volumes its volume GUID

Do you mean the disk hardware signature? Can I use the Unique id as an
universal identifier even better than the volume GUID?

Thanks
Francesco

4

>Do you mean the disk hardware signature? Can I use the Unique id as an

universal identifier even better than the volume GUID?
Disk Signature given by the Disk Class driver, 4-Byte number. This is not
guranteed to be unique across host. [This has changed with GPT disks].
Do you mean WWPN/WWNN as disk hardware signature?
I think Volume GUID is still a better option. But somewhere, I read you can
have multiple volume GUID for the same volume. I have never seen an example
of this.

-----Original Message-----
From: Francesco [mailto:xxxxx@acm.org]
Sent: Saturday, August 06, 2005 7:40 PM
To: Windows File Systems Devs Interest List
Subject: RE:[ntfsd] Getting a volume GUID

Pashupati Kumar wrote in news:xxxxx@ntfsd:
>
>>>2) Can I use IOCTL_MOUNTDEV_QUERY_UNIQUE_ID? I guess the ID I get is
>>>different from Volume GUID. Is it really unique?
>>
>> - Yes, unique id is different than the volume GUID. Unique id is given
>> by the volume manager controlling the volume. For Basic Volumes, its
>> disk signature + offset and for LDM/VXVM volumes its volume GUID
>
>Do you mean the disk hardware signature? Can I use the Unique id as an
>universal identifier even better than the volume GUID?
>
>Thanks
>Francesco
>
>—
>Questions? First check the IFS FAQ at
>https://www.osronline.com/article.cfm?id=17
>
>You are currently subscribed to ntfsd as: xxxxx@legato.com
>To unsubscribe send a blank email to xxxxx@lists.osr.com

5

> Do you mean the disk hardware signature?

No, the MBR partition table one.

Can I use the Unique id as an
universal identifier even better than the volume GUID?

For many purposes - yes.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com