A better floppy backup (was Re: Corrupted backup floppies from cpio)

[T. William Wells]

In article <3950 at encore.UUCP> bzs at xenna (Barry Shein) writes:
:
: The problem is that cpio is not a backup utility and it's
: irresponsible to use it as such.

You are so right.  In fact, I haven't seen anything that meets my
requirements for floppy backup so I am writing one.

I am looking for people to help me test this thing. Since it is going
to be my primary backup, I want it bashed on as much as possible
before commiting to it. Anyone who is interested should send me
E-mail at the address in my signature. This thing is being written on
a Zenith 386 under the latest Microport UNIX; if you are using a
different system, you may need to do some porting.  I will try to
make this program as general as possible, and to maintain any
reasonable ports.

Following is a longish description of the program; if you have any
comments or suggestions, feel free to send them along.  These should
probably be posted, rather than E-mailed, as a debate on their merits
would probably be useful.

---

The program `fbackup' takes several arguments. First, it must have
one of `brl', for backup, restore, or list. It may also have a `v'
argument to cause it to write additional information as it processes.

The output devices are specified with -d options and there may be
more than one of them.  They must be raw floppy disks, and the
program checks for this. If you don't specify any output devices,
there is a default.  The program pauses before writing to the first
output disk specified; it is up to the user to make sure that the
other drives are filled before the program gets to them.

Informational messages are written to standard out, error messages
are written to standard error, and instructions and queries relating
to the floppies are written to /dev/tty.

---

fbackup -b[fcv] [-n name] [-d device]...

Backup each file whose name is read from standard in.  The backup
specific options are:

   -c Compress the data as it is being written.  This saves space,
      but does make retrieving data in a damaged file impossible past
      the point of damage.

   -f Format each floppy before writing to it.  If an I/O error
      occurs while writing the floppy, Fbackup will attempt to
      reformat the bad disk; however, if your disks are known to be
      unformatted, this will save time.

   -n Specify a name for the backup. This name, along with the
      current date is stored on each floppy of the backup.

The program refuses to use a floppy disk which has any bad sectors.
Should it be unable to write the floppy disk, you will just have to
replace the disk with a new one.

Different versions of the program might write different format
backups; however, the backup format is designed so that newer
versions of the program can always read older backups.

---

fbackup -r[auv] [-n name] [-d device]... [files]...

Restore files from floppy disks. If no files are specified on the
command line, all files on the disks are restored.  If a directory
name is specified, all files under that directory are restored.

When directories are restored, should there be files in the directory
which are not noted in the backup, warnings will be printed.  Special
files can be restored, though normal permission restrictions apply.

Restoring will attempt to preserve as much information as it can.
This includes the user and group names, access times, and file modes.
Files which were linked when backed up and restored at the same time
will have the links recreated, if possible.  The backup stores the
user and group names, not the user and group ids, these are
translated back when the files are restored.

   -a Normally, leading slashes in the backed up file names are
      ignored, causing restores to be done relative to the current
      directory.  If this is undesirable, specifying -a causes the
      restore to be done honoring absolute path names.

   -n If this option is specified, the backup name on the disk is
      checked against the argument.

   -u Normally, the restore will not replace a file with an older
      version from the backup; the -u option will override this,
      causing the files to be restored regardless of the relative
      modification times.

The program is very tolerant. If there is an error reading data from
the disk, it will attempt to recover the error from the checksum
information. If a file is damaged, it will attempt to restore as much
of the file as possible. Even if a file is damaged, it will go on to
the next file. Since sequence numbers are maintained in the backup,
even if entire files are lost, you will be informed of how many are
gone.

Moreover, the program deals fairly reasonably with disks inserted in
the wrong order. Should you know that the files you want are on disk
three of the backup, you can just insert disk three. You will get a
warning, but the files will be restored anyway.

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fbackup -l[v] [-n name] [-d device]...

List the files on the disks. Without the -v option, just the names
are listed. With the -v option, the files are listed as if with an
ls -il.

---
Bill
{uunet|novavax}!proxftl!twwells!bill