scsi device files disappear after kernel relinking

[Philip Hall]

I wish to thank everyone that has helped me in the past.
I have yet another question however. Maybe some day, i'll have this machine
configured and running to my satisfaction.
The problem is:
i have an hp vectra rs20c with an esdi 150mb primary hard disk, running
sco unix v3.2.1.
I have installed a scsi adaptec 1540a with a wangtek tape drive which
works just fine.
I just installed an external 660mb cdc scsi drive as a secondary
hard disk. that went more or less smoothly also. 
i have it devided into three 215mb filesystems.
the problem is if I relink the kernel for any reason, the device files
for  my scsi disk are removed. i.e. 1s0, 1s1, ...
the tape device file is not removed however,  rct0 etc.
i have tried to put an r in the third field of the Sdsk enter in mdevice.
the man page for mdevice implies that i am not supposed to do this.
As a result of the device files being removed, i have had to do an mkdev hd
which results in the files systems being remade.
Another piece of info, (don't know if it is related), is upon booting,
the scsi disk is not shown in the configuration table that is displayed.
the adapter and scsi tape are, but not scsi disk.
the info concerning the disk is shown when the disk is first accessed.
anyone have any ideas as to:
1) prevent the device files from being removed,
2) failing that, having the device files automatically remade
  during new kernel installation.
3) why the entry for scsi disk doesn't appear in the
  config table which is displayed on booting.

as always
thanks in advance for any and all help.

Philip Hall
Sys admin
Data Prompt Inc.
Silver Spring Md.

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