How to get physical partition name from iSCSI details on Windows?
- by Barry Kelly
I've got a piece of software that needs the name of a partition in \Device\Harddisk2\Partition1 style, as shown e.g. in WinObj. I want to get this partition name from details of the iSCSI connection that underlies the partition. The trouble is that disk order is not fixed - depending on what devices are connected and initialized in what order, it can move around.
So suppose I have the portal name (DNS of the iSCSI target), target IQN, etc. I'd like to somehow discover which volumes in the system relate to it, in an automated fashion.
I can write some PowerShell WMI queries that get somewhat close to the desired info:
PS> get-wmiobject -class Win32_DiskPartition
NumberOfBlocks : 204800
BootPartition : True
Name : Disk #0, Partition #0
PrimaryPartition : True
Size : 104857600
Index : 0
...
From the Name here, I think I can fabricate the corresponding name by adding 1 to the partition number: \Device\Harddisk0\Partition1 - Partition0 appears to be a fake partition mapping to the whole disk.
But the above doesn't have enough information to map to the underlying physical device, unless I take a guess based on exact size matching.
I can get some info on SCSI devices, but it's not helpful in joining things up (iSCSI target is Nexenta/Solaris COMSTAR):
PS> get-wmiobject -class Win32_SCSIControllerDevice
__GENUS : 2
__CLASS : Win32_SCSIControllerDevice
...
Antecedent : \\COBRA\root\cimv2:Win32_SCSIController.DeviceID="ROOT\\ISCSIPRT\\0000"
Dependent : \\COBRA\root\cimv2:Win32_PnPEntity.DeviceID="SCSI\\DISK&VEN_NEXENTA&PROD_COMSTAR...
Similarly, I can run queries like these:
PS> get-wmiobject -namespace ROOT\WMI -class MSiSCSIInitiator_TargetClass
PS> get-wmiobject -namespace ROOT\WMI -class MSiSCSIInitiator_PersistentDevices
These guys return information relating to my iSCSI target name and the GUID volume name respectively (a volume name like \\?\Volume{guid-goes-here}), but the GUID volume name is no good to me, and there doesn't appear to be a reliable correspondence between the target name and the volume that I can join on.
I simply can't find an easy way of getting from an IQN (e.g. iqn.1992-01.com.example:storage:diskarrays-sn-a8675309) to physical partitions mapped from that target.
The way I do it by hand? I start Disk Management, and look for a partition of the correct size, verify that its driver says NEXENTA COMSTAR, and look at the disk number. But even this is unreliable if I have multiple iSCSI volumes of the exact same size.
Any suggestions?
