WMI query to select disk containing system volume - wmi

Question

I need to get some information (model and serial) of the disk that contains the system volume (usually C:). I'm using this query:
SELECT * FROM Win32_DiskDrive WHERE Index=0
My question is, is the disk with Index=0 always the disk containing the system volume?
Edit: I added an additional query to get the index of the disk containing the boot partition:
SELECT * FROM Win32_DiskPartition WHERE BootPartition=True
Then the original query changes to
SELECT * FROM Win32_DiskDrive WHERE Index={diskIndex}
I figured I'd be pretty safe this way. Suggestions for better solutions are always welcome :)

Answer 1

As stated, add an extra query to get the index of the disk containing the boot partition:
{diskIndex} = SELECT * FROM Win32_DiskPartition WHERE BootPartition=True
SELECT * FROM Win32_DiskDrive WHERE Index={diskIndex}
Unfortunatly WMI doesn't seem to support JOINs, which would have made the query a little more efficient.

Answer 2

My question is, is the disk with Index=0 always the disk containing the system volume?
In my case the answer is No. My system disk has index 1.
Also your assumption that the system disk is always bootable is incorrect.
$ wmic os get "SystemDrive"
SystemDrive
C:
$ wmic logicaldisk where 'DeviceID="C:"' assoc /resultclass:Win32_DiskPartition
...\\DZEN\ROOT\CIMV2:Win32_DiskPartition.DeviceID="Disk #1, Partition #0"...
wmic diskdrive where 'Index=1' get "Caption"
Caption
OCZ-VERTEX4 // Yes, this is my system disk.
Also your assumpion about BootPartition usage is incorrect for cases when bootmanager is on another disk, like in my case:
wmic partition where 'DeviceID like "Disk_#1%"' get DeviceID,BootPartition
BootPartition DeviceID
FALSE Disk #1, Partition #0
wmic partition where 'BootPartition="TRUE"' get DeviceID,BootPartition
BootPartition DeviceID
TRUE Disk #4, Partition #0
TRUE Disk #3, Partition #0
As you can see, nor the system disk neither one of bootable ones do not have Index=0 for my case. Actually I have Index=0 for the one of non system and non bootable disk.