John Poltorak wrote in a message to All:

 JP> Whilst installing a new scsi adapter, I came across a device
 JP> driver called nextdev.sys, which basically sets the letter
 JP> for the next device viz: 

 JP> device=nextdev.sys z

 JP> This allowed a VDISK to be accessed as Z: . Unfortunately,
 JP> it was a DOS program. Does anyone know of anything
 JP> comparable for OS/2? I would like to have something like
 JP> this for support situations, where I cannot know beforehand
 JP> which letter will be allocated for the VDISK. Anyone fancy
 JP> porting this little utility? 

This is an EXTREMELY bad idea under OS/2.  Drive letters are assigned in
the order in which their drivers are loaded.  It is possible to write a
driver that simply reserves a bunch of drive letters when it loads, but it
would interfere with certain types of file system drivers.  In addition,
even a do-nothing block device driver must support minimal functionality,
including the ability to respond intelligently to the standard request
packets, in order to avoid bad things such as hanging the boot process. 
OS/2 will also allocate real resources for the management of your
non-existent drives, will send them commands such as "get
partitionable fixed disks," "reset media," "read,"
and will generally expect real drives.

In particular, OS/2 remote (network) file system drivers request all of the
drive letters remaining after the local file system drivers have been
loaded.  By reserving a number of drive letters, it is quite possible to
exhaust the supply and stop network support from loading.
 
-- Mike


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