

              NOVELL TECHNICAL INFORMATION DOCUMENT

TITLE:              Backup - Tips and Tricks
DOCUMENT ID:        014945
DOCUMENT REVISION:  A
DATE:               01APR94
ALERT STATUS:       Yellow
README FOR:         NA

NOVELL PRODUCT and VERSION:
Novell DOS 7

ABSTRACT:

This document discusses undocumented tips and tricks used with
Backup.

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ISSUE

     Novell DOS 7 Backup - Tips and Tricks

     Question:

     I was backing up my hard disk to diskette and halfway
     through the backup, something went wrong.  I want to start
     the backup again.  Do I have to start the whole thing all
     over again, or can I just pick up where I left off?

     Answer:

     Novell DOS 7 does not include parameters for the BACKUP
     command to pick up where you left off when doing your
     backup.  One technique for accomplishing the same thing is
     described below.  However, understanding a little bit how
     BACKUP works with DOS files is necessary.

     DOS files have several attributes, which describe how DOS
     treats the files. These attributes are the following:

          Attribute           Code
          ---------------     ----
          Read only           R
          Hidden              H
          System              S
          Archive needed      A

     The attribute you are interested in here in this discussion
     is the "Archive needed" attribute.  If this attribute is
     turned on, it basically informs DOS that the file has
     changed since it was backed up last.  Any time you modify a
     file, DOS sets the "Archive bit" (the Archive needed
     attribute) so that BACKUP recognizes the file has changed. 
     When BACKUP is run, any file that is backed up gets the
     Archive bit turned off.  This way, DOS can keep track of


     what files need to be backed up again.

     How does this information help my backup?

     Let's assume, for this example, that you want to backup all
     files on the hard disk C: drive.  The normal backup command
     would be the following:

          C:\> BACKUP C:\*.* /S

     This command instructs BACKUP to do a backup of all files in
     all subdirectories on the hard disk.  As BACKUP runs, it
     will turn off the archive bit of any file that is backed up.
     Another backup command might look like this:

          C:\> BACKUP C:\*.* /S /M

     This tells BACK UP to do a backup of all files in all
     subdirectories, as in the preceding example.  However, this
     time, only files that have the archive bit set will be
     backed up.  So, let's assume that you issued the first
     command (without the /M) and the backup errored out on disk
     15.  If you used the second command (with the /M), you would
     be able to do a backup again without backing up the files
     that were successfully backed up on the first 15 diskettes.

     The only problem with this method is that other file may
     exist on the hard disk that are not backed up, that might
     not have the archive attribute set.  In this case, these
     files would not get backed up.  The following is a command
     to solve this problem:

          C:\> ATTRIB C:\*.* +A /S

     This command sets the archive bit on all files on the hard
     disk C: drive.  You use this command before doing the BACKUP
     command.  Now, if the BACKUP runs successfully, everything
     is fine.  If BACKUP does not run successfully, then all
     files that still have the archive bit set are the files that
     did not get backed up.  Any file that does not have the
     archive bit set was successfully backed up, because the
     BACKUP program turned off the archive bit.  Now, after the
     backup errors out, we can use the second BACKUP command
     (with the /M) and it will back up the rest of the hard disk.
     Every time the backup gets errors, all we have to do is use
     this BACKUP command, and you will get the correct files,
     that haven't been backed up yet.

     In summary, use the following two commands every time you
     want to do a backup.  Don't use just the BACKUP command:

          C:\> ATTRIB C:\*.* +A /S
          C:\> BACKUP C:\*.* /S

     If you get errors, then you can use the following command to
     get just the files that didn't get backed up before the
     error:

          C:\> BACKUP C:\*.* /S /M
