Re: VMS naming conventions for disk volumes?

From: L. Blunt (someone_at_out.there)
Date: 01/10/04 

Date: Sat, 10 Jan 2004 00:03:48 -0000

"Brian Chase" <bdc@world.std.com> wrote in message
news:btn68n$t11$1@pcls4.std.com...
> In article <btlmfs07mr@news1.randori.com>, L. Blunt <someone@out.there>
wrote:
>
> > eg: Put something like the following into systartup_vms.com:
> > $ define/system/translate=(conc,term) user_root
> > $disk1:[user.],$disk2:[users.]

I made a little error here, which I am surprised was not picked up on.

If you use the "/trans=terminal" qualifier (tells VMS to stop logical name
translation at this point) you cannot use other logical names (like
"$disk1") in the definition. You must provide real device names or not use
the "terminal" qualifier, the "/trans=conceil" is needed for root logicals
to work correctly.

> >
> > Then all SYSUAF accounts are defined using the location as
> > USER_ROOT:[username], and this is also what the user will see as their
home
> > (SYS$LOGIN) directory.
> >
> > Similarly you create other rooted logical names for specific uses, such
as:
> > PROJ_ROOT for development, UTILS_ROOT, etc... Using logical names like
this
> > is one of the reason why VMS systems are so easy to manage and maintain,
and
> > therefore require far fewer administrators/operators than just about
every
> > other OS. Being able to shift data/directories/applications/operating
system
> > locations, without having to edit/alter vast numbers or scripts,
databases,
> > and uaf entries. Just alter the logical names.
>
> I think the main requirement in this situation is that the systems's admin
> be clueful about their OS. :-) In Windows OSes, you've got the (albeit
> weak) option of mapping logical drive letters to provide a layer of
> indirection. Under Unix there's the fundamental ability of mounting
> filesystems anywhere into the directory tree, and also the ability to
> setup symbolic filesystem links as a form of indirection.

Agreed, there are some similar things available, but I freely admit to being
a VMS Bigot :^)

This main difference with logical names is that they are translated by VMS,
which makes them very flexible. Not just for directories, or single files,
but also queues (print and batch), devices (serial lines), and general
software seting/parameters (think Windows registry).

> One thing that I do like about what you've shown above though is the
> ability of a single logical to be mapped to multiple directories across
> volumes. You can get a similar end result under Unix using a filesystem
> automount facility or by using a directory of symlinks, but neither of
> those options are as elegant as your VMS logical example. I'm a little
> curious about how the precedence is handled when there's a name collision
> between files in too or more of the referenced directories, but that's
> either an RTFM or a "try it and see" answerable question.

Basically the list is searched in order until a translation that can satisfy
the command if found. When using this ensure that the user accounts do not
have the ability to create directories in the root directoy. This will
ensure that directory/file creation fails until the correct logical name
translation is reached.

> I've gotten a lot of good feedback on this thread both here and offline,
> so I want to thank everyone for their answers.
>
> At the moment, I'm primarily playing with a VS4000/VLC with a 1GB internal
> system drive. I'm going to add a second larger external disk to hold a
> combination of freeware and user accounts, with top level [USERS] and
> [SOFT] directories mapped to sensible logical names. When I get to the
> point of pulling some of my bigger systems into a cluster, I'll spread
> things out a bit more.
>
> -brian.
> --
> --- Brian Chase | bdc@world.std.com | http://world.std.com/~bdc/ -----
> IBM 1130 Club Motto: "Computer People Are Happy People"

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