-=> On 10 Mar 95  08:00:31 Mike Bilow said to John Poltorak <=-


 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.
I agree something to achieve this is definitely needed. I wanted to
add a hard disk to my system, and as part of the upgrade process,
wanted to move the CD away to its final letter first.


 JP> Anyone fancy porting this little utility?
I will do it if someone can provide me with DEVCON6 FOC. I have device driver
writing experience.

 MB> This is an EXTREMELY bad idea under OS/2.  Drive letters are assigned
 MB> in the order in which their drivers are loaded.  It is possible to
 MB> write a driver that simply reserves a bunch of drive letters when it
 MB> loads, but it would interfere with certain types of file system
 MB> drivers.  In addition, even a do-nothing block device driver must
 MB> support minimal functionality, including the ability to respond
 MB> intelligently to the standard request packets, in order to avoid bad
 MB> things such as hanging the boot process.  OS/2 will also allocate real
 MB> resources for the management of your non-existent drives, will send
 MB> them commands such as "get partitionable fixed disks,"
"reset media,"
 MB> "read," and will generally expect real drives.
 I would support the commands - even read and write could return EOF.
 Reset etc is easy.
I would be prepared to live with some overhead, but it would be better
to avoid assigning 512k byte caches.

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

Obviously! most of us just want to fix the drive letter of an existing
peripheral to a predetermined value, even if we change the number of
intervening devices - probably consuming one or two drives.

Andrew

 
... If love is blind, why is lingerie so popular?
--- Blue Wave/Max v2.12 OS/2 [NR]