Subject: Tbackup 0.8: backup system for Linux uploaded
From: [email-masked] (Koen Holtman)
Date: 10 Jun 1994 21:20:11 +0300
Newsgroups: comp.os.linux.announce

Tbackup (three backup) is a user friendly, fault tolerant package for
making backups of a Linux filesystem.  It is primarily designed to
make multi-megabyte backups to a set of floppy disks.  It has
incremental backups, backup indexes, selective restore, error
correcting codes, and more.

I have uploaded version 0.8 of tbackup to the following sites:

Site1        = ftp.win.tue.nl
Path1        = /pub/linux/tbackup          File1 = tbackup-0.8.tgz

Site2        = nic.funet.fi 
Path2        = /pub/OS/Linux/util/backup   File2 = tbackup-0.8.tgz

Site3        = sunsite.unc.edu
Path3        = /pub/Linux/system/Backup    File3 = tbackup-0.8.tgz

At this moment tbackup-0.8.tgz may still be in the incoming
directories on the last two sites.

Apart from bug fixes, tbackup 0.8 has several new features:

  - Error correcting codes for floppy disks.  The blexta (block level
    exor trace assembly) error correcting codes allow reconstruction
    of missing data if a backup floppy develops bad sectors.

  - You can make a `tbackup rescue disk', a floppy that allows easy
    reinstallation of tbackup if your Linux system on harddisk becomes
    unusable.

  - Supports a `select, backup and delete' strategy for freeing
    harddisk space.  You can move infrequently used stuff to floppies
    and do a selective restore if you need it again.

  - More support for tape users (requires a working Linux tape
    driver).

  - You no longer need to kill the kernel logging daemon before
    running tbackup.

  - `Extended floppy densities' allow backing up more data to a single
    floppy disk.  For example, the `extended double' density fits 820
    Kb on a 3.5" DD floppy.  This doesn't necessarily work with all
    floppies and drives, however.  Due to Linux kernel limitations,
    writing 1.7 Mb to a 3.5" HD floppy is extremely slow.

Part of the README file from tbackup-0.8.tgz follows:
------------------------------------------------------------------------

  tbackup -- general backup system for Linux.
  V0.8
  This is free software.  Use it at your own risk.

*** _1_ WHY NOT USE TAR?

Archiver programs such as tar(1), cpio(1) and afio(1) also allow making
backups to a set of floppy disks.   But tar stands for tape archiver,
it was not designed with floppy disks in mind.  You only need one tape
to back up a 100 meg hard disk.  But if you don't have a tape drive,
you need 50 or more floppy disks, and several things can go wrong:

1) disk 45 has a bad sector that can't be written to
2) disk 46 was not formatted 
3) you forgot to insert disk 50 and `pressed enter' with disk 49 in the drive 

Tar was not designed to handle such conditions gracefully.  It will
abort on errors 1) and 2), and will not warn you about 3).  The only
way to correct these errors is to start over again at disk 1, and that
is hardly acceptable.

Tbackup was designed to recover from all the errors above (and a lot more).

For small backups of say less than 5 floppy disks you can just as well
use tar (it is even slightly faster than tbackup), but for big backups
tbackup is better.

*** _2_ FAULT TOLERANT ARCHIVE FORMAT

Being able to quickly recover from errors when an archive is created
is nice, but not the most important aspect of a backup package.

It is the restore that really matters.  Like hard disks, the floppies
or tapes used for a backup can develop unreadable spots and give read
errors.  If this happens, the restore program should still be able to
recover as much information as possible.

If you use tar (with some auxiliary program like disksplit(1)) to make
compressed archives on a set of floppy disks, even a single read error
is disastrous.  If one sector on disk 5 is damaged, you not only
loose a part of disk 5, ALL information on disks 6-50 will also be
lost.  Compressed tar archives on tapes have the same problem.

Tbackup makes a fault tolerant kind of compressed archive: only the
the files in the archive are compressed, the file headers are left
uncompressed.  This way, a read error generally only causes the loss
of one or two files.

If floppy disks are used for the backup, tbackup can add error
correcting codes to the data on the floppy.  If a floppy then develops
unreadable spots, the restore program can often reconstruct the
missing data using the error correcting codes.  This way the the
entire archive can be restored even if there are some read errors.

*** _3_ OTHER ADVANTAGES

Apart from the error recovery mechanisms, tbackup has some other
advantages.

- No command line arguments needed:  I don't make backups all day, so
  I can't remember N options.  Tbackup asks for all relevant
  parameters and gives verbose explanations.  (You can still use
  command line arguments if you want to.)

- Hides details: You don't need to have any deep UNIX knowledge to
  use tbackup and understand its error messages.  In particular
  tbackup will hide the weirdness of the Linux floppy drivers. 
  (The drivers don't report write errors to the writing program!!)

- Customizability: You can set default values for parameters and
  preset parameters to a fixed value.

- Backup Index: A tbackup index file not only lists the files in an
  archive but also shows the numbers of the floppy disk the files were
  written to.  This is useful for making quick selective restores.

- Select, backup, delete: tbackup supports a select, backup and delete
  strategy for freeing up space on a nearly full hard drive.  You can
  move infrequently used stuff to floppies and do a selective restore
  if you need it again.

*** _4_ INSTALLATION

You have to be root to install tbackup, as the installation process
creates entries in directories that are owned by root.

1) For running tbackup, you need to have the following software:

     mtools
     fdformat
     gawk
     gzip
     afio (version 2.3.6 or higher)
     Optional: setfdprm for extended floppy disk formats

   The afio archiver program can be found at various ftp sites:

     nic.funet.fi    : /pub/OS/Linux/util/backup/afio-2.3.7.tgz
     sunsite.unc.edu : /pub/Linux/system/Backup/afio-2.3.7.tgz
     ftp.win.tue.nl  : /pub/linux/tbackup/afio-2.3.7.tgz

   Setfdprm seems to be included with all newer linux distributions, I
   don't know when it first appeared.

2) If you have no older tbackup version installed, go to 3).

   If you do have an older tbackup version installed, remove it first
   by typing
 
     rm -r /usr/lib/tbackup

   [...]

3) cd to the / directory and untar the tbackup archive.
   The files unpack to the directory /usr/lib/tbackup.

------------------------------------------------------------------------

Koen.

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