Peter Fitzsimmons wrote in a message to Coridon Henshaw:

 CH> In any case, how can I find out which physical disk a 
 CH> partition is located on and the disk subsystem type?

 PF> Use the category 9 ioctls (physical disk access) to read the
 PF> partition table and figure it out yourself.  This is the
 PF> only way I can think of without writing an *.FLT (a device
 PF> driver) that inspects the os2dasd.dmd drive chain. 

Actually, an FLT would have no knowledge necessary to do this.  Drive
letters are owned by the DMDs, and an FLT has no way of knowing which DMD
it is serving.  In theory, an FLT can be called from any DMD.  In practice,
a DMD must have access to its IORB pool in near fixed memory with
context-free addressability, which means that DMDs always allocate their
IORBs in their own default data segment, so an FLT could do some egregious
manipulations to figure out which DMD owns any given IORB.  Of course, FLTs
are free to do anything they want with an IORB, even servicing it
themselves or initiating their own, so trusting results that are usually
but not always valid is unwise.

 PF> The source code for os2dasd.dmd is on the DDK cdrom, and is
 PF> enjoyable reading for the very curious.

Or for the mentally deranged.
 
-- Mike


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