>I was under the impression that the way ADSM does restores with the newer
>clients (at some point of V2 and above) that DIRMC is no longer as
>beneficial as it used to be.   So I've been taking it out here.   Does
>anyone know for sure that can comment?

This was answered by an ADSM developer about a year ago.  Basically,
ADSM is able to store the complete info about a directory in the
database such that, like zero-length files, ADSM is able to reconstruct
them upon restoral without going to tape.  It is only when more
elaborate information is involved that directory info has to go to tape,
and be restored from tape.  Here are composite notes I've kept:

DIRMc                                   Client System Options file (dsm.sys)
                                        backup option to specify the Management
                                        Class to use for directories.  Basic
                                        directory information is stored in the
                                        ADSM database such that storage pool
                                        space is not required for it.  However,
                                        when an ACL (Access Control List) is
                                        associated with the directory, it is a
                                        like file data and so *does* need to be
                                        stored in a storage pool.
                                        This option was added because the data
                                        would get bound to the management class
                                        that has a copygroup with the longest
                                        retention period.  In many installations
                                        that was causing it to go directly to
                                        tape resulting in excessive tape mounts.
                                        The DIRMC option allows you to cause
                                        it to be bound to a management class
                                        whose copygroup destination is a disk
                                        storage pool so tape mounts are not
                                        needed until there is no space
                                        available in the disk storage pool.
                                        Performance: You could use DIRMc to put
                                        directory data into a separate
                                        management class such that it could be
                                        on a volume separate from the file data
                                        and thus speed restorals, particularly
                                        if the volume is disk.  Drawbacks are
                                        that directory data would more probably
                                        be on disk than on tape, as backups want
                                        to be; and if on tape, you would need
                                        two tape drives simultaneously (and
                                        double the mount time).

  Richard Sims, Boston University OIT