W2K3 : Volume Unique Id

Hi,

I have a Basic Disk whose Disk Signature is becoming 1 after an application
recovers some data ( not sure why ). The Volumes on this disk seem to be
usable. However, on a specific host, the Volume Unique Id of the Volume
seems to be a pretty long number. From what I understand, ‘FtDisk uses a
combination of MBR signature + partition offset as a unique ID’ . Is it
possible, in some circumstances, for ftdisk to use some other mechanism to
create this Unique Id ? Is Disk Signature being 1 triggers a different
workflow ? I tried forcing the Disk Signature to 1 on another host but that
does not seem to generate a long Unique Id. The host with long Unique Id
does not have SP 1, is it expected to have some impact ?

Also, when a Disk with a Signature of 1 is mirrored and surfaced on another
host with a same/different Disk Signature, IOCTL_MOUNTMGR_QUERY_POINTS
fails, Reason :[The parameter is incorrect] . Registry entry for Mounted
Devices does not get updated with any Volumes for the Mirrored disk even
after a wait for more than a minute. However, a Volume scan with
FindFirstVolume … does list the Volumes of mirrored disk at this time. This
behavior is observed whenever the Disk Signature of Source Disk is 1,
irrespective of the fact, whether it has Unique Id of Signature + partition
offset or a longer one.

Any thoughts explaining this behaviour ? Any inputs would be greatly
appreciated.

Thanks
yogita

Resend

From: Yogita Bijani [mailto:xxxxx@emc.com]
Sent: Friday, July 15, 2005 7:52 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] W2K3 : Volume Unique Id

Hi,

I have a Basic Disk whose Disk Signature is becoming 1 after an application
recovers some data ( not sure why ). The Volumes on this disk seem to be
usable. However, on a specific host, the Volume Unique Id of the Volume
seems to be a pretty long number. From what I understand, ‘FtDisk uses a
combination of MBR signature + partition offset as a unique ID’ . Is it
possible, in some circumstances, for ftdisk to use some other mechanism to
create this Unique Id ? Is Disk Signature being 1 triggers a different
workflow ? I tried forcing the Disk Signature to 1 on another host but that
does not seem to generate a long Unique Id. The host with long Unique Id
does not have SP 1, is it expected to have some impact ?

Also, when a Disk with a Signature of 1 is mirrored and surfaced on another
host with a same/different Disk Signature, IOCTL_MOUNTMGR_QUERY_POINTS
fails, Reason :[The parameter is incorrect] . Registry entry for Mounted
Devices does not get updated with any Volumes for the Mirrored disk even
after a wait for more than a minute. However, a Volume scan with
FindFirstVolume … does list the Volumes of mirrored disk at this time. This
behavior is observed whenever the Disk Signature of Source Disk is 1,
irrespective of the fact, whether it has Unique Id of Signature + partition
offset or a longer one.

Any thoughts explaining this behaviour ? Any inputs would be greatly
appreciated.

Thanks
yogita


Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

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