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6 Replies Last post: Nov 3, 2009 8:42 AM by sudarsan

Mapping disk to drive letter posted: Oct 21, 2009 1:16 PM

giladb

37 posts since
Mar 21, 2008

I am running on Linux, and inspecting a Windows disk.
How can my application find out what drive letter the disk is mounted on ?
Is VixMntapi_GetVolumeInfo the right API ?

Re: Mapping disk to drive letter

1. Oct 23, 2009 3:33 PM

in response to: giladb

giladb

37 posts since
Mar 21, 2008

Based on other posts it seems like VixMntapi_GetVolumeInfo is the right API.
However, it seems to always return zero numGuestMountPoints, regardless of whether I am checking for a disk with snapshots, without snapshots, when the VM is powered on or powered off.

Could this be another functionality that is not supported in Linux ?

Re: Mapping disk to drive letter

2. Oct 26, 2009 10:06 AM

in response to: giladb

sudarsan

263 posts since
Sep 20, 2006

Not sure what you are trying to do - but extracting such information from Windows (NTFS or FAT) volumes is not supported if the application is running on Linux - this is because VDDK uses Windows API's to parse the registry hives of the guest to get information like drive letters.

Thanks
Sudarsan

Re: Mapping disk to drive letter

3. Oct 26, 2009 10:20 AM

in response to: sudarsan

giladb

37 posts since
Mar 21, 2008

I am simply trying to obtain the drive letter where the disk is mounted.
Now I realize that this is not supported on Linux, a fact that is not clearly mentioned in the documentation.

Re: Mapping disk to drive letter

4. Oct 26, 2009 10:23 AM

in response to: giladb

sudarsan

263 posts since
Sep 20, 2006

OK, thanks. I will make sure I will get it documented.

Apologies for the confusion,

-Sudarsan

Re: Mapping disk to drive letter

5. Oct 27, 2009 12:36 PM

in response to: sudarsan

giladb

37 posts since
Mar 21, 2008

I am looking for additional clarifications
.
If I understand this correctly, VDDK roughly does the following thing
1. Obtains information about the volume
2. Accesses the Windows registry, and finds a drive letter (or letters) that match that information

Assuming that I do run on Linux, but have my own hook to access the registry, is there a way for me to find this mapping ?
I know where the information is in the Windows registry, but I don't know how I can correlate this with information I have from VDDK.

Thanks

Re: Mapping disk to drive letter

6. Nov 3, 2009 8:42 AM

in response to: giladb

sudarsan

263 posts since
Sep 20, 2006

It is a bit convoluted, hopefully you can make it all work:

You need libraries to parse the NTFS and / or FAT
You also need code to parse the mbr and get the offsets for the volumes
Looking at the MBR, you can find which is the system volume - and from here get either boot.ini or boot bcd.
Once you have the volume offsets, you can parse the ntfs / fat file system structures to get to the boot.ini (or bcd hive) and look for the boot volume (the one that has windows directory)
You can then read the registry file and parse it in anyway you like

There are some additional issues with dynamic volumes - but once you have the above working, it is not that difficult.

Thanks
Sudarsan

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