From: leichter@lrw.com (Jerry Leichter)
Newsgroups: comp.os.vms
Subject: re: Splitting a user disk
Date: 15 Dec 92 13:11:05 GMT
Distribution: world
Organization: The Internet


	I have a series of DEFINE statements in SYLOGICALS.COM like the
	following:

	$ DEFINE/SYSTEM/EXEC/TRANSLATION=(CONC,TERM) STUDISK      MOE$DUB0:

	and I've told my users to use logical name and not the physical device
	name in command procedures, etc., because the physical device *will*
	change from time to time.

	Diskquotas are enabled on the current device (and will be on the new
	pair of devices).  The users' directories are created for them in the
	MFD when their accounts are created.  The users are not allowed to
	created directories outside their initial login directory.  

	The time is rapidly approaching when I will need to split the current
	users of "STUDISK" into two groups due to the facts that STUDISK has
	recently surpassed 90% full and that it is overbooked by a factor of
	more than 8!

	I would *like* to maintain the logical name of STUDISK for all current
	users of the device.  Here is what I envision doing:

	  Split the current users on DUB0 onto DUB1 and DUB2.  A current (and
	  future) user will have diskquota and directory on *only one of* DUB1
	  or DUB2.

	  For my convenience:

	    $ DEFINE/SYSTEM/EXEC/TRANSLATION=(CONC,TERM) STU1      MOE$DUB1:
	    $ DEFINE/SYSTEM/EXEC/TRANSLATION=(CONC,TERM) STU2      MOE$DUB2:

	  The default device in SYSUAF will be STU1 or STU2.

	  And to maintain the current logical STUDISK:

	    $ DEFINE/SYSTEM/EXEC/TRANSLATION=(CONC,TERM) STUDISK   -
	  	MOE$DUB1:,MOE$DUB2:

	This *appears* to work, i.e., DIR STUDISK:[000000] shows all files in
	the MFD of both devices.  A bonus (I think) is that they show up as a
	single list, not as separate lists as seen with DIR SYS$MANAGER, etc.
	Also,  DIR STUDISK:[some-valid-directory] lists the files in that
	directory as expected.

	Is there anything obvious that I'm missing?  Or worse, anything
	insidious?

There are any number of situations in which this will not work quite as
expected.  For example:

	- Files created using the STUDISK: logical will ALWAYS go into
		MOE$DUB1: - when looking for an EXISTING file, RMS searches
		all elements of a search list, but when CREATING a file, it
		always uses the first element.  Note that this will happen
		even if you try to create a file in a directory that only
		exists in the second member of the list!

	- Setting default to a search list can produce unexpected results.

	- Doing file specification defaulting when search lists are involved
		requires care.  If it's done properly through RMS, there's no
		problem; but there are many programs around (no VMS standard
		ones, but plenty anyway) that try to use the resultant
		file specification string to get defaults for the next
		parse.  They won't work properly with search lists.

		In particular, it is just about impossible to do correct
		file specification defaulting in the presense of search
		lists within DCL.
		
All in all, expect to be answering a lot of questions from puzzled users of
programs that USED to work.

		    Or is there a better way?

I know there are many people on this list who dislike them, but this strikes
me as an ideal application for a bound volume set.
							-- Jerry