Hacker Chronicles 2/HACKER2.BIN/076.COLUM04.TXT

Text File | 1993-07-30 | 21KB | 475 lines

     Backing Up is Hard to Do

     By Ken Johnson, Chicago Computer Society

     "Thou Shalt Back Up."  This is one of the cardinal rules in
     computing:  making duplicate copies of important files and
     storing them in a safe place.  Unfortunately, backing up is often
     like flossing or eating broccoli -- something you know is good
     for you but that you don't do (or don't do often enough)!
     However, backing up doesn't have to be a chore.  We'll look at
     some approaches and alternatives that make backing up easier.

     This article will focus on "software" methods that backup to
     floppy disks.  In terms of speed and power, floppy backup can't
     compete with backup hardware such as tape drives.  But backup
     hardware is expensive and may require some technical expertise to
     get started.  We'll look at using software (DOS or other
     programs) to get you started backing up right away.

     First, you need to develop a backup strategy.  When developing
     the strategy that best suits your needs, consider the following
     points:

     1.  You don't have to back up the entire hard disk every time.
     You should do a full backup when starting out.  But you can do
     incremental backups that will only backup those files that have
     changed.  DOS' BACKUP and XCOPY commands let you select only
     changed files; commercial backup utilities also have this
     capability.  By subsetting only the changed files your backups
     are less time consuming, and you're more likely to do them.

     2.  Backup data files, not necessarily program files.  Chances
     are what is most important to you is your data, not the programs
     that created that data.  The program files can always be restored
     from the original disks (the ones they told you to put in a safe
     place, remember?).  For example, I keep a lot of CCS information
     in Paradox databases.  I back up those files regularly, but I am
     less concerned with backing up the actual Paradox system files.
     Those I can always copy back from the original disks.

     To make it easier to back up data files, you probably will want
     to keep them separate from the program files.  This is easy to do
     on a hard disk -- simply create separate subdirectories.
     Depending on the number and size of files in these
     subdirectories, you may be able to do a simple COPY *.* to backup
     the entire subdirectory to a floppy disk.

     3.  Don't forget the floppies!  Your backup strategy also should
     include data files kept on floppy disks.  Too often we associate
     "backing up" only with hard drives.  If you keep important
     information on floppies, they also must be backup up. Floppies
     are more susceptible to damage because they are outside of the
     computer and more exposed to dangerous elements:  magnetic
     fields, spilled coffee, children looking for frisbees, etc.

     Luckily, backing up floppies can be easy.  Just use DOS' DISKCOPY
     command for a quick and simple backup.   DISKCOPY makes an exact
     duplicate of the disk, copying all files (including hidden and
     system files), the volume label, and duplicating any directory
     structure.

     You can use DISKCOPY even if you have only one drive.  If you
     specify one drive or no drive with the command, the disk in that
     drive (or in the default drive) is copied to another disk in the
     same drive.  You'll be prompted to swap disks.

     4.  Use batch files to automate backing up (however you choose to
     do it).  Anything you can do to automate the process of backing
     up is good, because it means that you are more likely to do it.

     For example, let's say that you have your Wordperfect data files
     segregated into a separate subdirectory on your hard drive called
     WPDATA.  You can create a batch file to use WordPerfect, then
     copy all the files in WPDATA to a floppy disk in the A: drive:

          ECHO OFF
          CD WPDATA
          C:\WP51\WP
          ECHO Place the WordPerfect backup disk in Drive A:
          ECHO Press Ctrl-Break if you don't want to back up right now
          PAUSE
          XCOPY C:\WPDATA\*.* A:

     "Echo Off" suppresses the display of the DOS commands as they
     execute.  The next two lines change to the WPDATA subdirectory
     and load WordPerfect (which is in a subdirectory called WP51).
     After you exit WordPerfect the Echo commands tell you that a
     backup is going to take place and pauses execution until you
     press a key.  This allows you time to put in the disk.  (Notice
     that you can Control-Break to stop the batch file at this point
     and thus not do the backup).  Finally all the files in the WPDATA
     subdirectory are copied to the disk in the A: drive using XCOPY.
     XCOPY is faster than COPY because it uses all available RAM for
     the copy.

     Now lets take a look at some approaches to backing up your files.


     Using DOS BACKUP and RESTORE

     The first, but perhaps the least attractive approach to backing
     up your files is using DOS' own BACKUP and RESTORE.  These DOS
     commands are probably what put most people off backing up.  They
     are cumbersome to use and have annoying restrictions (especially
     in DOS versions before 3.3).  Many software vendors make a good
     living by selling programs that keep you from having to deal with
     BACKUP and RESTORE.  One "advantage" of BACKUP/RESTORE though is
     that they are free and easily accessible on your hard drive.

     The BACKUP command copies files in a special format, and large
     files can be split over multiple floppy disks.  Because of the
     special format, files can only be retrieved and restored with the
     RESTORE command.

     The BACKUP command syntax is:

     BACKUP [source_drive:][filespec] destination_drive: [/S] [/M]
     [/A] [/D]
     DOS 3.3 added these switches: [/T] [/F] [/L]

     /S -- backs up files from the selected and all child
     subdirectories.

     /M -- backs up only those files modified since they were last
     backed up.

     /A -- adds backed up files to an existing backup diskette.

     /D:mm-dd-yy -- backs up files created or modified on or after the
     date specified.

     /T:hh:mm:ss -- used with /D to backup files on or after the time
     specified.

     /F -- formats the destination disk if it is not already
     formatted.

     /L[:filespec] -- creates a log file that lists the backed up
     files.  If a filespec is not specified, then a file called
     BACKUP.LOG is created in the root directory.  If the log file
     exists, new entries are added to the end.

     Some examples:

     BACKUP C:\*.* A: /S
     -- this does a complete backup of all files on the hard disk C:
     to floppy disks in A:.

     BACKUP C:\*.WK1 A: /S /M
     -- backs up all files in all directories (/S) with an extension
     of .WK1 that have been changed since the last time they were
     backed up (/M).

     BACKUP C:\*.* A: /S /D:01-01-91 /L:C:\BKUP91.LOG
     -- backs up all files on C: created or modified on or after
     January 1, 1991.  The file c:\BKUP91.LOG will contain a list of
     the files backed up.

     The RESTORE command syntax is:

     RESTORE source_drive [target_filespec] [/S] [/P]
     DOS 3.3 added these switches:  [/M] [/N] [/B] [/A] [/E] [/L]

     You must specify the source drive (the floppy drive).  The
     "target" is the original filespec, including the full path, from
     which the file was backed up.  It may include wildcards.

     /S -- restores all files that match the target filespec,
     including all files in child subdirectories.

     /P -- prompts to make sure you want to restore (overwrite) a file
     that has been changed since it was backed up or files marked
     Read-Only.

     /M -- restores only files modified or deleted since the last
     backup.

     /N -- restores only files that do not exist on the target; in
     other words will not overwrite any files.

     /B:mm-dd-yy -- restore files modified on or before the specified
     date.

     /A:mm-dd-yy -- restores files modified on or after the specified
     date.

     /E:hh:mm:ss -- restores files modified at or earlier than the
     specified time.

     /L:hh:mm:ss -- restores files modified at or later than the
     specified time.

     Some examples:

     RESTORE A: C:\*.* /S
     -- all files backed up are restored from the disks in drive A:.
     You will be prompted to insert the backup diskettes in sequence.

     RESTORE A: C:\DBASE\*.DBF
     -- all files with an extension of .DBF which were originally
     backed up from the \DBASE subdirectory will be read from drive A:
     and written to the \DBASE directory of drive C:.  If that
     directory doesn't exist on C:, it will be created.

     RESTORE A: C:\*.* /S /P /A:01-01-91
     -- restores all files modified or deleted after January 1, 1991.
     You will be prompted before any files on C: that have been
     changed since the backup, or are marked read-only, are restored.


     BACKUP and RESTORE changed in DOS 3.3 to make them a little more
     user friendly.  BACKUP can now format disks while backing up.  In
     version before 3.3 you had to make sure you had enough formatted
     disks before starting.  If you ran out of formatted disks you had
     to abort and run BACKUP again.  In DOS 3.3 you tell BACKUP to
     format with the /F parameter; in DOS 4.0 BACKUP will
     automatically format the floppy disks if necessary.

     BACKUP in DOS 3.3 also works faster and more efficiently than
     older versions by combining small files into one large file.  It
     also creates a control file to tell RESTORE how to take this
     large file apart and restore it properly.  BACKUP also can create
     a log to tell you where your files are on the backup disks.

     RESTORE in DOS 3.3 lets you restore files that have changed or
     have been deleted since the backup, or files no longer on the
     hard disk.  You also can restore based on date and time.  Another
     change in DOS 3.3 is that RESTORE will not restore the DOS system
     files IBMBIO.COM, IBMDOS.COM (or their generic counterparts), and
     COMMAND.COM.  This is a plus, since it prevents you from
     inadvertently restoring the wrong version of DOS.  To complete
     the restore you'll need to use the SYS command to put IBMBIO.COM
     and IBMDOS.COM back on your hard disk, and then copy COMMAND.COM
     over.

     If you are using a version of DOS before 3.3, you may want use
     the /P switch when doing a restore.  This will prompt you before
     files marked read-only are restored.  You can answer NO for
     IBMBIO.COM and IBMDOS.COM, then use SYS to copy these files over
     from your original DOS disks.

     As you can see, BACKUP and RESTORE aren't the easiest things in
     the world to use.  If you don't want expense of buying a backup
     utility but still want to stay away from BACKUP/RESTORE, consider
     using XCOPY as an alternative.


     Using XCOPY as an alternative to BACKUP

     If you are using DOS 3.3 or 4.0, XCOPY is a friendlier
     alternative to DOS' BACKUP command.  Not only is it much faster,
     but copied files can be restored with the COPY command (in other
     words, you don't have to mess around with RESTORE).

     There are a couple of things to keep in mind when backing up with
     XCOPY.  XCOPY cannot copy files larger than a single diskette
     (BACKUP is the only DOS choice then).  It will not copy hidden
     files.  XCOPY does not overwrite files on the target diskette, so
     the disks need to be formatted and empty.  Finally, if you want
     to backup all files, you need to use ATTRIB to set the archive
     attribute on for all files before starting XCOPY.

     The syntax for XCOPY is:

     XCOPY d:source_filespec d:target_filespec [/S] [/E]
     [/D:mm-dd-yy] [/A or /M] [/P] [/W] [/V]

     /S -- copies files in child subdirectories as well as the
     specified directory.

     /E -- creates empty directories on the target, even if no files
     are copied into those directories.

     /D:mm-dd-yy -- copies only those files with a modified on or
     after the date specified.

     /A -- copies only those files with the archive attribute turned
     on.  This indicates a file that has been modified.

     /M -- does the same thing as /A, but resets the archive attribute
     after the copy.  You can use either /A or /M, but not both.

     /P -- prompts you before each file is copied.

     /W -- waits for you to insert a disk into the source.

     /V -- files are verified as they are copied.

     When using XCOPY for a backup, you will need to use the /M switch
     and reexecute the command as the disks fill.  When XCOPY fills a
     disk, it will stop with a "disk full" message.  Repeat the
     command, filling disks until all files have been backup up.
     (Remember that /M turns the archive attribute off after a file is
     copied.  Therefore when you reexecute XCOPY files already copied
     are ignored).

     It is easiest to do an XCOPY backup with a batch file.  In DOS
     3.3 XCOPY will set ERRORLEVEL to 4 for a "disk full" error.  You
     can check for the ERRORLEVEL then loop back through the batch
     file:

     REM XCOPY Backup Batch File, DOS 3.3 only
     @ECHO OFF
     CLS
     ECHO -- XCOPY full backup of C: drive --
     ATTRIB +A C:\*.* /S
     :loop
     ECHO Insert blank, formatted disk in A: drive
     PAUSE
     XCOPY C:\*.* A: /S/M
     IF ERRORLEVEL 4 GOTO loop
     ECHO -- All Done --

     Let's take a closer look at this batch file.  The ATTRIB command
     turns on the archive attribute for all files on the C: drive.
     The ECHO and PAUSE tell you to insert a new disk and press a key
     to continue.  XCOPY copies all files with the archive attribute
     on to the A: drive, and turning the archive attribute off as the
     copy is done.  When the disk in A: fills, XCOPY ends with an
     ERRORLEVEL of 4.  This causes the batch file to loop back to the
     ECHO and PAUSE commands, then reexecute XCOPY.  Since the archive
     attribute has been turned off for files already copied, those
     files are ignored on each subsequent time through the batch file.

     When all files have been copied, the batch file ends with the "--
     All Done --" message.

     Unfortunately, you can't use this batch file with DOS 4.0.  In
     DOS 4.0 XCOPY no longer sets an ERRORLEVEL code when the disk
     fills.  You can still use a batch file, but you have to stop the
     batch program manually:

     REM XCOPY Backup Batch File, DOS 4.0 only
     @ECHO OFF
     CLS
     ECHO -- XCOPY full backup of C: drive --
     ATTRIB +A C:\*.* /S
     :loop
     ECHO Insert blank, formatted disk in A: drive
     ECHO or press Ctrl-Break if done . . .
     PAUSE
     XCOPY C:\*.* A: /S/M
     GOTO loop

     You'll notice that instead of checking ERRORLEVEL, this batch
     file does an unconditional loop (and will continue to loop
     indefinitely).  You'll have to monitor the XCOPY and manually
     break out of the backup with Ctrl-Break.


     Using PKZIP/PKUNZIP to Backup and Restore

     This is a personal favorite of many users.  PKZIP is a shareware
     program from PKWARE that compresses multiple files into a single
     "ZIP" file.  Not only is storage space reduced, but the single
     ZIP file makes file group identification and transportation
     easier.  This is why zipped files are so popular on bulletin
     board systems.

     Of course, the compressed files are not useable in that form.
     You use the companion program PKUNZIP to uncompress or extract
     the compressed files.  PKUNZIP also can selectively extract
     individual files, display the files on screen for viewing, or
     print files to the printer.

     The basic command syntax for PKZIP is:

     PKZIP [options] zipfile [files . . .]

     zipfile -- is the name (and location) you give the ZIP file.  The
     default extension is .ZIP.

     files -- is the names of the files to compress; the wildcards *
     and ? can be used.

     PKZIP has a number of options that can be specified when creating
     the ZIP file.  See the PKZIP documentation for a full
     description.  Among the options useful for a PKZIP backup are:

     -a -- adds files to new or existing ZIP file; same named files
     will overwrite those already in the ZIP file.

     -u -- updates an existing ZIP file with files only if they don't
     exist in the ZIP file or if they have a date later than same
     named files already in the ZIP file.

     -r -- recurse through specified subdirectories and all child
     subdirectories.

     -wHS -- includes hidden (H) and system (S) files in the ZIP file.

     At present, PKZIP does not can not create a single ZIP file which
     spans multiple disks.  You'll need to do selective file backups
     using PKZIP, ensuring that each compressed file will fit on one
     floppy.  If you have your data files organized into
     subdirectories as suggested above, PKZIP can easily be used to
     backup individual subdirectories into separate ZIP files.  Batch
     files are especially useful for this.

     For example, I prepare my training materials in WordPerfect,
     saving them into a subdirectory called \TRAINING.  I have created
     a batch file that will start WordPerfect in that subdirectory,
     then zip all the files when done:

     ECHO OFF
     CD TRAINING
     C:\WP51\WP
     ECHO Insert backup disk in drive A:
     ECHO Press Ctrl-Break to stop before backup
     PAUSE
     PKZIP -u -wH A:TRAIN.ZIP C:\TRAINING\*.*
     ECHO  *** ALL DONE ***

     This file updates the zip file on the A: drive called TRAIN.ZIP
     with new and changed files from my \TRAINING subdirectory.
     Notice that I use the -wH option to include hidden files.  I use
     a utility program that lets me give 60 character filenames to my
     files, and it creates a hidden "library" file in the subdirectory
     that I need to include in the ZIP file.

     You could create similar batch files for each application you
     work with regularly, backing up each data subdirectory after
     using the application program.  Once set up, it's so easy that
     you will have no excuse not to backup!


     Using a Backup Software Program

     Probably the easiest (if most expensive) backup strategy is to
     buy a backup software utility.  These programs generally list for
     under $150, with "street prices" lower.  Backup utilities tend to
     be simple to learn and use, with a menu-driven interface for both
     backing up and restoring.  They are capable of some level of
     configuration, which allows you to save customized backup "sets"
     for repeated use.  Most can format disks on the fly.  Many
     support a mouse for added convenience.

     Many backup utilities also offer as data compression, which
     minimizes the number of disks you have to use.  They also use the
     dual Direct Memory Access (DMA) mode for efficiency.  This mode
     allows the computer to read from your hard disk and write to the
     floppy disk simultaneously, thus making backups much faster.

     The most popular backup utilities are probably Fastback Plus from
     Fifth Generation Systems, Norton Backup from Symantec Corp., and
     PC Tools Deluxe/PC Backup from Central Point Software.  An
     October 15, 1990 Product Comparison by InfoWorld rated these the
     top three backup utilities of the seven tested.


     Conclusion

     Backing up doesn't have to be a chore.  You need to give serious
     thought to developing a backup strategy to deal with the real
     possibility of damaged disks and lost data.  You might think that
     your hard disk won't crash and that you'll never encounter a
     destructive virus.  But also remember that backups can help you
     recover from small disasters like static electricity scrambling a
     file or your fingers typing DEL instead of DIR.

     Using DOS' BACKUP and RESTORE can be intimidating and not
     entirely successful.  I've tried to present some approaches to
     backing up that can make it easier to do on a regular basis --
     segregating data files in separate subdirectories; using XCOPY or
     PKZIP; automating backup with batch files; buying backup utility
     programs.

     Whatever method you might use, I hope you will develop a backup
     strategy, put it in place, and do regular backups.  Remember,
     there are two kinds of computer users:  those who have had disk
     crashes and those who haven't had disk crashes YET.  Now if I can
     just get you to eat your broccoli . . . .