Change windows partition device number as reported by cygwin stat

cygwin;diff()gptinodepartitioning

I have two partitions with the same device number:

$ stat -c "%D" /cygdrive/c
ec6d967e
$ stat -c "%D" /cygdrive/g
ec6d967e

I believe this is because G: was restored from an image of C:. C:\cygwin64 is mounted on /. When I try to run diff -r / /cygdrive/g/cygwin64 then it skips over directories with the same device + inode number. This is not a bug in diff, per this bug report:

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=33467

So how can I change the device number for the G: partition? I tried using gdisk 1.0.4 but no luck; the unique disk and unique partition GUID's were already different in each case.

I'm using Windows 7 Bootcamp and the partitions have the same device number as each other in OS X 10.6.8 as well, although they are different from the Cygwin device number.

Best Answer

Under Cygwin with an NTFS filesystem, the device number comes from the NTFS Volume Serial Number. There is a tool called VolumeID from Microsoft that lets you change it.

https://docs.microsoft.com/en-us/sysinternals/downloads/volumeid

$ fsutil fsinfo ntfsinfo g: | grep NTFS
NTFS Volume Serial Number :       0xe3462385ec6d967e

$ ./Volumeid64.exe g: 8f70-e8b5

VolumeId v2.1 - Set disk volume id
Copyright (C) 1997-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

Volume ID for drive g: updated to 8f70-e8b5

$ fsutil fsinfo ntfsinfo g: | grep NTFS
NTFS Volume Serial Number :       0xe34623858f70e8b5

Unfortunately it doesn't change under OS X. I'm happy enough being limited to Cygwin for now. On the other hand, this tool only changes the last 4 bytes of the serial when it is an 8-byte field.

https://www.ntfs.com/ntfs-partition-boot-sector.htm

I was unable to find a command line tool to set the full 8 bytes. However, AOMEI Partition Assistant can handle it, and apparently DiskGenius can too.

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