Oakland CPM Archive/oakcpm.iso/cpm/hdutl/backmw.dqc/BACKMW.DOC

Text File | 1985-02-10 | 9.5 KB | 231 lines

DOCUMENTATION FOR BACKMW.COM v2.50

BACKMW is (c) S. Kluger, 1984. The object code has been released into
the Public Domain and may be distributed freely, except for profit.

1. WHAT IS BACKMW

BACKMW is an incremental backup/recovery utility written for Morrow's
M16 hard disk system (hence the MW in BACKMW). It can be used on any
hard disk system provided that:
    - the DPB of the highest logical drive includes all lower
      logical drives as RESERVED TRACKS
    - the hard disk does not have more than 1000 cylinders

BACKMW is used once to toally back up the complete hard disk onto
floppies, then it can be used periodically to update the information
backed up. It automatically keeps track of CRC values for all cylinders
and will back up only those cylinders that have been written to since the
last backup. While BACKMW can be used for partial recovery, writing back
to the hard disk only those cylinders that have changed since the last backup,
it is really intended for catastrophic failures, such as trashed logical
drives or a complete reformat.


2. OPERATION

BACKMW has four options, which are displayed in the main menu when
the program is started. Those options are:

T - total hard disk backup
I - incremental hard disk backup or restore
C - configuration parameter editor
Q - quit to CP/M


Simply select one of the above choices. Note that you must do a total
backup of your hard disk before you can do any incremental backups or
restores.

3. THE CONFIGURATION EDITOR

The editor is presented first, because your system may be different from
the default and you should first configure BACKMW for your environment.

Selecting the C command first displays the current configuration parameters
which default to my system environment:

    High hard drive       : E:
    Floppy backup drive   : F:
    CRC file drive        : F:
    Number of CYLINDERS   : 306       (306/432 is the data for the
    Number of SECTORS/CYL : 432        Morrow M16 system)

    CHANGE? (H,F,C,T,S,Q,?)

Simply type the appropriate letter to change an option (a "?" explains
the option letters) or use "Q" to exit the editor. After exiting, you may
optionally save BACKMW to a new file (you get to specify drive and file name).


4. TOTAL BACKUP

After selecting "T", you will be asked to input the size of your floppy
disks in k bytes. Be sure to enter an accurate value and that all floppy
disks you will be using during the backup process have AT LEAST that
much room left! You will receive a caution message if you select a floppy
size of less than 256k, but may go ahead with the operation anyway. Next,
BACKMW will tell you how many diskettes you need to back up the complete
hard disk. You should make sure you have enough floppies. While you can
abort BACKMW at any prompt (and, therefore, also while backing up), it is
not advisable to abort BACKMW in the middle of a backup operation, since
you cannot continue where you left off at a later date - you would HAVE TO
restart backup from scratch.

Next, you will be asked for an 8-character DISK ID, which can be almost
anything, but you might want to make it the current date. This 8-character
string will be used by BACKMW to construct the filename for the cylinder
files and the CRC file. The name MUST be 8 characters exactly.

You will now be prompted to insert the first floppy diskette and backup
will commence. During backup, the following information will be displayed
for each cylinder:
    - cylinder number
    - sector being read (updated continuously while reading)
    - CRC value for the current cylinder

After BACKMW has determined that no more cylinders will fit on the current
floppy, you will be prompted to insert the next floppy and the cycle will
continue until all cylinders have been backed up. At 432 sectors per
cylinder, each cylinder takes approximately 30 seconds, so an M16 hard
disk can be backed up in about 2 1/2 hours.

When BACKMW has finished the backup operation, it will prompt you to insert
the floppy on which the CRC file should be written. IF THERE IS SUFFICIENT
ROOM, you should write this file to the very first disk backed up. Otherwise,
send it to a disk not used in the backup process. The CRC file contains
8 bytes for each cylinder, so in the case of an M16, you must have at least
4k to store the file! Do not write the CRC file to the hard disk, for
obvious reasons!


5. INCREMENTAL BACKUP / RECOVERY

If you select "I" at the main menu, you will be asked whether you want a
BACKUP or RECOVERY operation. Backup means FROM HARD DISK TO FLOPPY,
and recovery means FROM FLOPPY TO HARD DISK. Any response other than "B"
or "R" will return you to the main menu.

BACKMW will immediately ask you to insert the floppy which contains the
CRC file, and it will read the CRC file into memory. Next, you will be asked
for the starting cylinder number. This allows you to do partial backup/restore
or continue a previously aborted incremental B/R. The operation you selected
(B/R) will begin immediately. BACKMW CRC-checks each cylinder on the hard
disk, displaying status information as it goes. If the CRC calculated in not
the same as the value in the CRC file, BACKMW will attempt to open the
appropriate cylinder file on the floppy and transfer the information in that
file back onto the hard disk if RESTORE was selected, or it will update the
cylinder file on the floppy disk if BACKUP was selected. If BACKMW cannot
find the cylinder file, it will prompt you to insert the appropriate disk
(by number) until it finds the file.

After finishing an incremental BACKUP, BACKMW writes the CRC file back
onto the disk it read it from. No CRC file is written after a RESTORE
operation.

CONTROL-C can be used to abort the incremental B/R operation at any time.
When aborting a BACKUP, be sure to allow BACKMW to write the CRC file!!!
BACKMW will want to write the CRC file after an aborted RESTORE too, but
you may abort this before writing.


6. EXIT

BACKMW performs a warmboot when executing the Q command.


7. ERRORS

BACKMW will abort to the main menu any time a READ, WRITE, or OPEN error
is encounteded. The filename which caused the error will be displayed.

Should an error be encountered during hard disk write, a BIOS ERR R/W message
will be displayed and BACKMW will execute a warm boot.


8. MISCELLANEOUS

I have tested BACKMW on an M16 system. While testing, I inadvertently
clobbered my directory on A: and I was able to use BACKMW to restore it,
which proved to me that it worked. Even though I have used the program
many times and it appears to work fine, please use it with caution.
Be sure to do a conventional backup before using it for the
first time. Ideally, the following should be done to test the program, but
since I run a RCPM I don't have the time to do it:

    1. do total backup
    2. run a whole disk checksum (like the TEST command in POWER)
    3. clobber about 50% of the data on the drive
    4. do an incremental restore
    5. verify that whole disk checksum produces the same
       result as in (2) above.

If you setect any bugs, failures, strangenesses, please let me know with an
exact description of the problem. Verify that the problem is not random.


9. CREDITS

Thanks to frank Wancho for suggesting the incremental backup method
Thanks to Rick Conn for SYSLIB
Thanks to whoever uses it and reports success/failure



                        Dallas, TX, 06-24-84

ADDITIONAL NOTES: (this used to be BACKMW.NOT)

For more info read BACKMW.DOC

(updated 6/24/84)


TOTAL hard disk backup should ideally be done only once, unless more
than 40% of the hard disk has been changed. Since total foolproofing
of BACKMW would have added to the complexity and size of the program,
I have decided not to incorporate any BDOS error trapping. This means
that you MUST be absolutely sure that when you do a total backup,

1. All floppy disks you are about to use are EMPTY, freshly formatted
2. All floppies have the same capacity and you specify that capacity
   when BACKMW2 asks for it
3. You never make any silly mistakes such as leaving the drive door
   open, reversing the disk etc,

for if you do you will be forced to restart from scratch! On an M16
system that means you have to spend another 2 1/2 hours, PLUS the time
it takes to ERA *.* all diskettes again!


Now, now... don't let those little problems keep you away from a
free program...

VER 2.2:

A number of bug fixes in the incremental routine, which caused the system
to hang, access the floppy at the wrong time and mess up the CRC file.
A ^C abort feature was added to the incremental routines, where the CRC
check of the current cylinder can be aborted at any time. When aborted,
you will be asked to insert the CRC file diskette and the CRC file will
be updated in accordance with your actions.


VER 2.3:

V2.3 now runs on banked CP/M plus systems. BIOS calls are made through
BDOS call 50 IAW the CP/M plus calling conventions.


VER 2.5:

BACKMW version 2.5 no longer supports the buggy "manual" restore mode
introduced in v2.4. When doing an incremental backup or restore, you
are now asked for a starting cylinder number. This way you can interrupt
your work at any point and continue later without CRC checking hundreds
of already-processed cylinders.
This version will not insist on writing the CRC file if you run a
RESTORE to completion. Aborting an incremental function with ^C will
still result in the CRC file prompt. BE SURE to write the CRC file
after aborting an incremental BACKUP!