[OpenAFS-devel] Re: OpenAFS: conventions for new @sys? (rs_aix43 s390_linux22)

[R. Lindsay Todd]

Nathan Neulinger wrote:

> How bout a much more capable facility than @sys... Extend that concept
> into what the old apollo workstations had - dynamic symlinks. Why not
> make that part of AFS. i.e. support more than just @sys.
>
> For example, alot of sites would probably find '@acsys' to be useful to
> do the autoconf determined sys type.

It would be great to have dynamic symlinks, or something akin to VMS' logical
name facility, but I think such changes would involve more than just the file
system.  But we've found many times a need for something more flexible than
@sys.

Allowing additional magic names would be helpful, but I think even more useful
would be a magic name that could match one of several patterns, with different
weights assigned to each pattern.  Then the match with the pattern with the
highest weight wins.

So, for example, @arch attempts to match the name that best matches the
architecture of the running platform (say, linux-2.2).  You build a complex
system in AFS, and use a system like package or depot to copy files from or
make links to a copy in AFS.  Later, you discover that you have dependencies on
glibc, or KDE vs. GNOME, or something else you had not anticipated, which
causes this software to fail on systems you install later.  So add an expansion
for @arch on these newer system that encapsulates this difference, and give it
a higher weight.  Rebuild only those applications in AFS for which there is a
problem with the newly-discovered dependency; leave everything else alone.  You
package scripts, etc. do not need to change.

You really can't anticipate all the possible reasons for which you'll need to
differentiate systems.  @sys does a good job with most of the differences that
AFS needs; that is why I suggest using other magic names.

> I dunno exactly, but it seems like making a more general purpose
> mechanism would be very useful.
>
> -- Nathan
>
> ------------------------------------------------------------
> Nathan Neulinger                       EMail:  nneul@umr.edu
> University of Missouri - Rolla         Phone: (573) 341-4841
> CIS - Systems Programming                Fax: (573) 341-4216

--
R. Lindsay Todd                          email: toddr@rpi.edu
Senior Systems Programmer                phone: 518-276-2605
Rensselaer Polytechnic Institute         fax:   518-276-2809
Troy, NY 12180-3590                      WWW:   http://www.rpi.edu/~toddr