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Chapter 10.
The X-DOS Backup/Restore Program
Introduction
X-DOS includes a powerful menu driven Backup and Restore utility.
If you have had the unfortunate experience of hard disk crashes
or accidentally destroying files, you will appreciate this easy
to use yet fast and reliable BACKUP & RESTORE utility. This
program can be used to save all your hard disk data on floppy
disks allowing you to later restore this data if the original
data on the hard disk becomes corrupted or is deleted.
Backup main features
* Fully menu driven and help available at all levels.
* Supports MS-DOS command line compatible switches.
* Compress data in a very efficient way.
* Supports Backup to any kind of removable floppies
* Diskette backup preview to efficiently calculate the number of
diskette(s) needed for backing up.
* Directory tree and selection by including or excluding files.
When to Use Backup
When you should use backup depends mainly on how valuable your
data is. You can never be too careful about data integrity and it
is always a good idea to backup data as soon as it has been
updated or created on your disk.
It is a good idea to keep different backups according to data
that is frequently changed and data that is important to your
computing activities but which never changes. For instance, you
might decide to backup your utility directory of your disk and
put the diskette(s) in a safe place. Then every day or every few
days, make a backup of the files that have only been changed to a
great extent. Remember also to use at least two sets of diskettes
(minimum) when you are backing up. Never backup up on to the
latest diskettes.
Methods of Backing Up Data
Different backup methods are possible when using XBACK. They are
described here:
Full Backup
In this case, select all the files from the tree selection
regardless of whether the files were changed or not. If you set
the option to reset archive bit afterwards, all the files will be
marked as backed up.
10-1
Incremental Backup
In this method you are supposed to have made a first set of the
full backup once that is kept safe. The incremental backups will
backup only the files that have been changed or new files. In
this method, you must set the archive bit to Yes. The next
incremental backup will only backup the new files or modified
files since the last backup.
Differential Backup
This method also supposes that a full backup has been made
previously. However, it will make backup of files that have been
changed since the first full backup. As a result, you must set
the Reset Archive Bit option to No.
Starting XBACK
The X-DOS backup command is called XBACK. You can activate the X-
DOS BACKUP program by typing XBACK at the command line with no
parameters. In order to maintain compatibility with MS-DOS XBACK
has a predefined alias of BACKUP which means you can also run
XBACK by typing BACKUP at the DOS prompt. This is for the benefit
of users who are used to the BACKUP command and whether you type
BACKUP or XBACK as the command makes no difference to how the
program works.
XBACK will prompt you with the main menu and you can choose from
one of its main features, mainly BACKUP or RESTORE. XBACK can
also be activated with parameters defined as follow :
Command Syntax:
BACKUP [d1:][path][filespec] [d2:] [/ or - params]
Parameters:
[d1:][path] - is the drive and path to the files you want to
backup.
[filespec] - is the range of files you want to backup.
[d2:] - is the floppy drive you want to backup to.
[params] - are any of the switches described as follow :
Available XBACK Switches:
/, - B - starts backing up the specified range of files (default
*.*).
/, - D - prompts you for a date and backs up files modified on
or after your specified date.
/, - E - enables an audible prompt for diskette changes and
10-2
messages.
/, - I - resets the archive attribute on files that are backed
up.
/, - M - only backs up files that have changed since last
backup.
/, - O - gives overwrite warning if diskette already contains
data.
/, - P - enables packing of data, greatly reducing the necessary
number of backup diskettes.
/, - R - starts restoring mode.Insert last backup diskette from
set.
/, - S - includes any sub-directories to the specified filespec.
/, - V - verifies that data can be read from the backup
diskette(s).
/, - Y - includes system and hidden files in the backup.
Setting and Resetting Default BACKUP Switches:
The BACKUP command lets you set your preferred default switches
with the SET BACKUP=/switches command. To make the default switch
settings permanent, include the above statement in your
AUTOEXEC.BAT file.
Here is an example which will make BACKUP give an audible prompt
(/B) and pack your data onto fewer diskettes (/P) as default:
SET BACKUP=/B/P
BACKUP provides a delimiter (-) which gives you an easy way to
turn off a BACKUP option which is either turned on as default or
turned on with the SET BACKUP=/switches command. To change the
Overwrite Prompt option from its default Yes to No, just execute
BACKUP with the -O switch.
Using the BACKUP feature of XBACK
Most of the use of XBACK concerns the BACKUP function. We surely
hope you will not need to use the RESTORE feature too often!
You can either access the BACKUP function from inside XBACK at
the top menu or by calling BACKUP at the command line.
Choose the devices
The first thing before you actually start backing up is to select
which drive you wish to backup and where it will be backed up.
10-3
You can change the devices definition by activating the 'Devices'
command.
The first item lets you change the hard disk drive. Type in the
hard disk drive that you wish to backup. The default window will
probably display 'From C: to A:'. If you type D, it will change
to 'From D: to A:' and so on.
The 'Change Floppy Medium' will toggle the type of floppy you are
using to which ever possibility exists. You could for instance
decide to put 360K diskettes in a 1.2 Mb drive.
File Selection
Once the devices are chosen, it is necessary to choose what files
will be selected for backup. By default, XBACK performs a full
backup, so all the files are selected. Several methods are
available to select or unselect files.
Directory Choice
This method will display a tree structure of you drive with the
directory names on the left window and the files available in
that directory in the right window. You can scroll in each window
by using cursor keys or a mouse and change window by either using
the TAB key or by clicking in the opposite window with the mouse.
If you are in the directory window, you can select or deselect
the entire contents of the current directory as well as all the
subdirectories by typing the [ENTER] key or by clicking on its
name with the mouse. Alternatively, if the directory was
deselected, clicking on it or typing [ENTER] will select it
again.
If you are currently in the File window, You can select or
deselect files individually by clicking on them or typing
[ENTER].
When you either select or deselect a file or a directory, you
will see in the upper part of the window the number of files and
number of kilo bytes changing accordingly.
System files
This option will simply take into account files that have the
system and/or hidden attribute set and will make them available
for selection.
Date selection
This option let you select files that have a date equal or
superior to the one you specify in the Selection Date Window. If
you specify a date and then return to the directory selection,
you will find that some files that were previously selected have
been unselected by the date filter.
Archive Bit Set
10-4
This option is necessary if you intend to perform an incremental
or differential backup. The Archive Bit is set if a file is
modified or created. As a result, selecting files with the Bit
Archive Set will only select files that have not been backed up
since the first full backup.
You must decide between differential or incremental backup by
setting the Reset Archive Bit to No or Yes accordingly.
Options
Several options are offered to you to tune your Backup procedure.
Reset Archive Bit was previously discussed and concerned the
difference between differential and incremental backup.
The Overwrite Feature is a security feature that will warn you if
the destination diskette already contains data and prompt you to
continue or change diskette.
The Data Compression is important for the speed and diskette
consumption ratio. When data compression is used, the space
consumption on the output diskette is greatly reduced. It is hard
to predict how much will be gained since it depends of the nature
of your data, but you should at least gain 30% in disk space.
Data compression, however, needs substantially more time to
backup given the algorithm used to compress. You may choose
between the two methods according to either the number of free
diskettes you have or how much time you are willing to spend in
front of your PC when backing up.
The Verify Option simply checks if the data can be read again
after writing. It is a security feature but it is also costly in
time.
The Beep Option will turn on or off the sound when the user is
prompted by XBACK.
See Total
If you do not wish to modify the file selection, but still want
to view how many Kilo Bytes of data will be backed up and/or how
many files have been selected, you can activate the 'See Total
Command' to force XBACK to load the file structure and update its
data.
Backup Preview
The backup preview will simulate a real backup taking into
account the files selected and compression, but will not write
any data to the actual diskette. This option is available for
those of you that wish to know exactly how many diskettes are
needed, since estimating the number of diskettes required when
data compression is on can be totally meaningless.
Start Backup
10-5
When your file selection has been made and all your preferences
and switches are set accordingly, you can start the backup with
this function.
XBACK will display a screen that monitors the number of files and
kilo bytes backed up with their names in the bottom part of the
screen, directories on the left and files on the right. On the
upper right part of the screen, it will show the current diskette
number as well as its rate of filling.
When the current diskette is full, XBACK will prompt you to enter
a new diskette in the drive.
Using the Restore Feature of XBACK
The same principle applies to the BACKUP and the RESTORE in terms
of device configuration and file selection. They will therefore
not be repeated here.
In order to restore a previous backup, XBACK is expecting you to
put the last diskette in the diskette drive in order to rebuild
the directory tree. If you have lost this diskette or if it
happens that it is completely destroyed, you don't have to worry.
XBACK has a feature where it can reconstruct files even if the
last one is not available.
When the last diskette is available and in order, XBACK will used
the saved tree structure to reconstruct the file names and paths.
You will then be able to select files and directory as you did
with BACKUP before you decide to restore files.
If the last diskette is not available, things are a little bit
more complicated. When the last diskette is missing, XBACK does
not know how many files are present in the backup diskettes. It
will prompt you to insert the first diskette until the last one
available with you. At the last one, press 'D' to tell XBACK that
it was the last diskette. From then, XBACK will reconstruct the
tree structure and you will be able to make selections as before.
Directory Option
XBACK has a feature to display the directory of backed up
diskettes without activating the Restore function. You will be
prompted to input the last diskette of your backed up diskettes
(or the first one if the last is not available). Each directory
will be displayed one at a time and you will be prompted to
continue visualizing the tree.
Compare Option
The compare option may be needed to check which files have
changed since the previous backup. XBACK will prompt you to
insert the last diskette of the previous backup to reconstruct
the tree. Then input the diskettes one at a time starting with
10-6
the first one.
XBACK will compare the file from the backup and the one available
in your hard disk at the same location as defined in the path of
the backup file. The file may be the same, it may contains
differences or its length may be different. In any case, XBACK
will detect any changes between the files and report them to you
in the left window of the screen.
10-7