/sys$common/syshlp/helplib.hlb MOUNT, Qualifiers, /REBUILD  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /REBUILD (default)
       /NOREBUILD

    Controls whether or not MOUNT performs a rebuild operation on a
    disk volume.

    If a disk volume is improperly dismounted (such as during a
    system failure), you must rebuild it to recover any caching
    limits that were enabled on the volume at the time of the
    dismount. By default, MOUNT attempts the rebuild. For a
    successful rebuild operation that includes reclaiming all of
    the available free space, you must mount all of the volume set
    members.

    The rebuild may consume a considerable amount of time, depending
    on the number of files on the volume and, if quotas are in use,
    on the number of different file owners.

    The following caches may have been in effect on the volume before
    it was dismounted:

    o  Preallocated free space (EXTENT cache)

    o  Preallocated file numbers (FILE_ID cache)

    o  Disk quota usage caching (QUOTA cache)

    If caching was in effect for preallocated free space or file
    numbers, the rebuild time is directly proportional to the
    greatest number of files that ever existed on the volume at
    one time. If disk quota caching was in effect, you can expect
    additional time that is proportional to the square of the number
    of entries in the disk quota file.

    If none of these items were in effect, the rebuild is not
    necessary and does not occur.

    If you use the /NOREBUILD qualifier, devices can be returned to
    active use immediately. You can then perform the rebuild later
    with the DCL command SET VOLUME/REBUILD.

    For information about how to rebuild the system disk, refer to
    the OpenVMS System Manager's Manual.

    Examples

    In this example, the volume WORKDISK is mounted on NODE$DKA2.
    Because the volume is found to have been improperly dismounted
    and the /REBUILD qualifier is in effect, MOUNT displays a message
    and proceeds to rebuild the volume.

    $ MOUNT/REBUILD NODE$DKA2: WORKDISK
    %MOUNT-I-MOUNTED, WORKDISK         mounted on _NODE$DKA2:
    %MOUNT-I-REBUILD, volume was improperly dismounted; rebuild in
    progress

    In this example, the volume WORKDISK is found to have been
    improperly dismounted, but because the /NOREBUILD qualifier is
    specified, a rebuild is not performed. Instead, MOUNT displays a
    message to inform you that the rebuild is needed, and proceeds to
    make WORKDISK available for use as is. You can rebuild the volume
    later with the DCL command SET VOLUME/REBUILD.

    $ MOUNT/NOREBUILD NODE$DKA2: WORKDISK
    %MOUNT-I-MOUNTED, WORKDISK          mounted on _NODE$DKA2:
    %MOUNT-I-REBLDREQD, rebuild not performed; some free space
    unavailable; diskquota usage stale