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New Disk Manager Utility for VM

  Elia Perotto PPE/RD

DLIST is an aid to the VM user who has several minidisks and often reaccesses them in order to change the search sequence. Its name (DiskLIST) is similar to FLIST (FileLIST) and RLIST (ReaderLIST), of which simulates the behaviour. DLIST can be abbreviated to DL. The HELP information is available on PF1 inside DLIST.

Disks can be accessed, released, defined, formatted, detached and linked without loosing track of the whole situation. On each disk a FILELIST (or FLIST) session is possible, and XEDIT is usable inside FLIST. All transient and resident CMS commands are available from XEDIT or FLIST, like COPY, ERASE, RENAME, and so on.

Temporary disks may be defined with PFK 5 and formatted. A copy of a whole disk is possible with PFK 12, defining target and source disks with the cursor (tab + PFK 12). A clear indication of the free MBytes (not blocks which are dependent on blocksize) available on each disk is presented, and intensified if it is the largest in the screen, which shows 18 disks on a standard 3270, and more on 3278/9 and 3179.

Accessed disks appear first, then linked but not accessed disks, with the same information as accessed ones less the number of files, and then the ``Catalog Disks'' follow (disks not linked, but available).

The most useful feature of DLIST is the ``Disk Description File''. The Disk Description File is called DLIST INDEX and an example is on the same disk as DLIST, which contains the most used CERN disks. The format of the records is:

  col.  1-6   = Disk Label (6 bytes)
  col.  7     = Attribute byte 
                (blank or ``\%'' for highlight)
  col.  8-29  = Disk description 
                (up to 22 bytes)

In the attribute field, if the ``%'' is used, the intensified field ends at the first blank, and ``--'' is translated to blanks inside the intensified field (used to intensify a whole line).

Records with a blank in column 1 are pointers to a ``Catalog File'' which should reside on the same disk to avoid the case that it is on a disk that is not accessed. The pointer record's format is the following:

  col.  1     = blank
  col.  2-9   = Catalog File name
  col. 10-17  = Catalog File type

The search mode is ``*'' to search on all accessed disks; if several disks have a Catalog file with the same name and type, the first in alphabetical order will be used. Reversing the order of the disks will receal the other Catalog file.

Records in the Catalog file contain logical disk names (VMS-type, up to 12 characters) which can be linked to and accessed just by typing the mode letter into the mode field, or any other character (in this case the mode is the first free one starting with ``H'', the address used to link to the disk is the first free address from 192 to 1AF).

Care must be taken if a catalog disk is already linked or accessed, because it still appears on the Catalog, and one can link and access it more than once. The format of the catalog record is:

  col.  1-12  = Logical Disk Name
  col. 13-16  = Logical Disk owner Address 
                (4 bytes right-justified)
  col. 17-24  = Logical Disk owner Userid
  col. 25     = Field attribute (\% or blank)
  col. 26-80  = Disk description 
                (up to 55 bytes)

All DLIST INDEX files are read, on all accessed disks, which permits rarely accessed disks to have their own one-record DLIST INDEX.

Each user can have his own DLIST INDEX, and the Group Disks can have a group specific DLIST INDEX.

Only two Catalog Files are read: first and last specified (they must have different names or types). This because these files are intended for system and group use. If a user wants to describe a set of disks in addition to the system or group catalog, he can copy one of them, and add the necessary records. For any suggestion or request on this utility, send mail to ELIA@CERNVM.

next up previous
Next: DXCERN News Service Up: General Previous: Password Security on

Janne Saarela
Tue May 16 14:52:44 METDST 1995