ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/cpm/walnut-creek-CDROM/CPM/Z280/ZDAM-100.DOC

Text File | 2000-06-30 | 6KB | 110 lines

 ZDAM                    Direct Access Monitor

                             Introduction


Nearly  every owner of a hard disk has faced the problem of how to keep
accurate records and save back-up copies of the files contained on  the
hard disk. The problem is complicated by the relatively small amount of
storage  space afforded by floppy disks as compared to the large amount
of data stored on hard disk systems.

Z-System Direct Access Monitor (ZDAM) is an attempt to provide  orderly
record keeping, mount and dismount requests for files not currently on-
line,  and hard disk archival and restoration.

ZDAM  takes  much of its intrinsic functionality from  main-frame  file
management systems. The need to keep "all files on-line" will no longer
be  a requirement under this system.  Files which are requested and are
not on-line,  will cause the system to "prompt" the system operator, in
the case of Remote Access Systems (RAS) -- the sysop, to mount a floppy
disk in a specified floppy drive.  It may be that a floppy will have to
be first removed and "stored" before a new floppy can be mounted.

ZDAM is a "mount" oriented system:  all disks, hard disks and floppies,
must be specifically mounted or dismounted to protect the system from a
inadvertent malfunction.  Many people will consider this to be a rather
painful restriction. However, it will provide the necessary controls to
manage ALL disks directly on the system. It will generally speed up the
management of the disks, since the system will inherently know when any
file has been added, deleted or modified.

Each disk which can be mounted on the system will have a master catalog
entry and an on-line directory of its contents.  Filenames too, will be
kept  in a master catalog,  complete with flags about availability  for
remote file transfers, date of last backup, retention period, frequency
of  backup,  cyclic redundancy check,  currently on-line or archived on
floppy,  and  so forth.

Disks will be "numbered" and/or named,  will contain a system date, and
for the most part, have a system time which will indicate the last time
it  was modified.  The master catalogs will be updated as each disk  is
mounted  or  dismounted  to indicate the availability of the  files  it
contains.

ZDAM  will  undoubtedly be implemented as a Resident  System  Extension
(RSX) for CP/M and compatible systems. The current plan is to have ZDAM
intercept  BDOS calls which perform various file manipulations.  If the
file  is on-line,  ZDAM will provide the mechinism to access the  file.
Files not on-line, will be searched for in the master catalog. Once the
file has been located, a request will be made of the system operator to
"mount"  the  disk  and then file data will then be  presented  to  the
requesting  program.  Special "extended System Calls" will be  provided
for use in application programs.


                              Background

The Cedar Mill Z-Node has approximately 500 DSDD 8.00", 250 SSSD 8.00",
300 DSDD 5.25" and 250 5.25" SSSD diskettes in its inventory.  The hard
disk (currently 60MB and being expanded to 120MB) receives new files on
a daily basis.  Existing files are often edited, modified or moved from
one area to another. Keeping accurate records and back-up copies of the
files is practically an impossible task.

The  current procedure consists of first numbering (and dating) each of
the floppy disks which can be used by the system. Initially, of course,
they  are empty.  As files are entered on the disk,  a catalog of  each
floppy disk is created by MCAT. A complete SD directory listing of each
disk is made. These two lists, then, are used to manually control where
any given file from the hard disk will be archived.

None of the existing file catalog or archive utilities provide adequate
controls for managing a relatively large collection of files.  Although
there  are some techniques,  they all lack automated  procedures.  Many
people have indicated that such a management system is badly needed. It
is hoped that ZDAM will provide such a mechanism and management system.
It is anticipated that files contained in .ARC,  .ARK,  or .LBR  files,
along  with  stand alone files, will be handled equally well.

The reader must understand that this system is in its initial stages of
of planning and development.  For this reason,  the internal  functions
and exact relationship of ZDAM to the operating system have not reached
the stage of actually flow charting and designing a finished product.

Since this is a major undertaking, as much user input or feedback as is
possible is of utmost importance. Two positions for this system will be
considered.  Firstly, the case of a standard single-user system without
a remote access or bulletin board system. Secondly, the case for remote
access systems. In the former case, protection and security is not much
of an issue. In the latter case, it is of utmost importance.

In order to facilitate as much input or feedback as possible,  download
this file and distribute it to any of the remote systems which you use.
Please leave a message to the respective sysop so that he/she will read
the file.  Responses,  should be sent in the form of an electronic data
file  (private  upload preferred) or left as a PUBLIC message  on  this
system.  It  is hoped user response will play a major role  in  shaping
this new product. Whether the system remains public domain or becomes a
proprietary product, depends largely upon user support. If users do not
support the development, the system will be available by purchase only!

                         G. Benson Grey, Sysop
                         Cedar Mill Z-Node  24
                     12275 NW Cornell Rd, Suite 5
                       Portland, OR  97229-5611

                         [503] 641-6101 voice
                         [503] 644-4621 data