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AF's backup system

This is a client-server backup system offering several workstations a centralized backup to special backup servers. The backup on the clients can be started automatically using cron-jobs on the clients, but the more intelligent solution is to start it remotely from a central administrative host. To be independent of tricks like rsh, rcp and so on, that are in fact security holes, this remote start option is implemented internally. This is done because normally the backup has to be run with root authorization, otherwise files that are read protected by users would not be backed up. Any streaming device can be used for writing the data to it. The only thing it must be able to do is to distinguish between several files on tape so that it can be positioned directly.
Writing backups is normally done sequentially: The next writing to tape goes to the end of the previous write no matter from where you have restored in the meantime. There is a special possibility for the administrator to change the next writing position, but this should be done only in emergency cases (See: PROGRAMS, "cartis"). Another way to be more flexible here is to configure variable append mode.
A more thorough introduction can be found in the file INTRO, all changes in comparison with earlier releases are listed in the file Changes.

afbackup has been tested on Linux, AIX, IRIX, FreeBSD, Digital Unix (OSF1), Solaris and HP-UX. The clientside has also been tested on SunOS, OpenBSD and MacOS-X. Using Solaris < 2.6 as server is discouraged.

DISCLAIMER

These programs come without warranty. Everybody using this software does so at his or her own risk. The C-code has nonetheless been running over a year without problems and should have no bugs - at least if there are, they didn't hurt any backup or restore. The scripts for installation and configuration have been added later and might have bugs (but lots of testing has been done of course).

PLEASE

Can someone (-: PLEASE :-) do me a favour and:

  • tell me, if she or he finds unusual, strange or simply wrong English anywhere in my text. (This is a permanent request due to ongoing development of this software and thus the documentation)

FEATURES

  • Client/Server System
  • Authentication of the client is performed before it can take over control (see INSTALL and FAQ) -> security
  • Several servers can be configured for each client: the actual server is chosen by availability
  • Multi stream server, several clients can store to one server at the same time
  • Remote start option -> centralized administration
  • Access restriction for the streamer device -> security
  • Client-side per-file processing -> reliability. If the files and directories were first packed and then processed, by the server a single faulty bit in the processed stream would make the rest of the backup unaccessible for restore
  • Built-in compression (requires libz)
  • Data stream is written to tape in pieces of configurable size -> fast finding of files during restore
  • Tape position logging for each file -> fast finding of files during restore
  • Tape capacity is fully used
  • Flexible tape handling and configurable append mode
  • Full/incremental backups and verify
  • Raw partitions can be saved
  • Ordinary users can run the restore for their own files and directories, but only for these
  • Emergency recovery on different catastrophe levels
  • Command output saving feature: useful e.g for databases
  • Cartridge locations database maintained
  • Support for media changers
  • Client access to cartridge sets can be restricted

WHAT YOU NEED

GNU make. Others may not work, but all should (thanks to autoconfig). Using gcc is recommended.

A streaming device. This can be either a cartridge handling system or a simple drive. In the latter case you might want to maintain several cartridges nonetheless. Just buy them and write numbers to them starting with 1. The backup server will supply you with email when a tape must be put in and which it should be. The number of cartridges is configurable.

E.g. a compression program on the client side, if you want to use the processing feature and no built-in compression, which is not mandatory.

Some space for the logfiles. All the names of the saved files and directories are written to log files, which could grow to a notable size if a lot of files are saved.

For media changer support an appropriate driver command is necessary, e.g. mtx or stctl. They can be obtained from the same place, where afbackup had been downloaded.

INSTALLATION

See: INSTALL

UPGRADE

See: UPGRADE

Updates can be obtained from the following places:

ftp://ftp.zn-gmbh.com/pub/linux
ftp://ftp.sbs.de/pub/tools/afbackup
ftp://ftp.vic.com/af
ftp://www.man.torun.pl/pub/backup/afbackup ftp://ftp.iphil.net:/pub/mirror/afbackup

CONFIGURATION

See: CONFIG, INTRO and HOWTO.FAQ.DO-DONT

BEFORE YOU START

... Your first backup! Put your tape cartridge number 1 into the drive or make your cartridge handling system do so. If you don't want this or can't persuade your cartridge handler to do so, find out the number of the cartridge which is currently inside the drive. Then enter the following commands on the backup server (the host, to which the drive is connected) replacing <num> with the real cartridge number:

$BASEDIR/server/bin/cartis <num>
$BASEDIR/server/bin/cartis -i <num> 1

The first command tells the server the number of the cartridge, that is currently in the drive. The second one says: Write the next backup to the named cartridge, file 1 (the data stream is written in pieces==files to tape). See: PROGRAMS. $BASEDIR always stands for your chosen installation directory, corresponding to the particular tape device.

WHAT CAN BE STARTED: PROGRAMS

See: PROGRAMS

LIMITATIONS AND KNOWN BUGS

  • Under certain circumstances the label_tape command starts a mail program, that reads stdin, requires the user to press Ctrl-D and then sends an empty mail. Currently it is not understood nor analyzed in detail, why this happens. It might as well be a configuration error, but currently it must be treated as a bug
  • Directories should be traversed in parallel, when on different filesystems
  • A real index should be maintained, not only the probably compressed filelist, preferred implementation design: a special index server not bound to the client or server host
  • It should be possible, that several devices share a pool of tapes like in most jukeboxes
  • There are too many warnings written to the logs, that can be safely ignored
  • There is a strange problem with the multi-stream server on Digital Unix and probably others, that is not understood yet. There the multi-stream server should be started to run as a daemon (see: FAQ Q37)
  • On FreeBSD an probably other Intel-Unixes the optimization for the processor architecture i686 breaks the server side functionality on PIII multiprocessor systems and probably others. As there's not much performance increase achieved by fancy optimizations the use of such compiler options is generally discouraged, -O2 is ok, but you're better off refraining from heavier stuff like -march=i686.
  • Also on FreeBSD using threads breaks proper operation with newer DDS-4 drives. If you are using a drive like these and are experiencing problems especially at end of tape, rebuild the server with threads disabled. See the INSTALL file how to achieve this or use the Install script, that provides a special choice. These problems have been observed on FreeBSD version 4.7 - 5.0 with gcc-pre-3, probably this is in fact a gcc problem. Anyway if there's a chance to put the afbackup server on a Linux box, this should be done. Sorry, i'm aware that the FreeBSD-freaks will flame me now, but facts are facts.

No other bugs known. At release time there are never known bugs.

Please report bugs and suggestions for new features to:

af@muc.de

If you have problems, please add the last lines of the file(s) .../client/var/backup.log and .../server/var/backup.log to your posting, if present. Please add everything, too, that you think might be important.

If you want to be informed about important changes or bugfixes, monitor the desired releases on
http://www.sourceforge.net/projects/afbackup

TO DO

Reduce the limitations.
Port the client side to other platforms. Enhance jukebox support

CONTRIBUTIONS

  • restore.pl

Toivo Pedaste contributed the perl script restore.pl, a specialized replacement for afrestore. To work with the individual configuration, it needs some adjustments, see the first lines of the script for hints. The functionality:

This is a Perl program I use for restoring files. You give it a string, and it displays which files on the backups have names containing the string and on which tapes they are, and you select which one to restore.

Currently it only works for a single file or directory.

  • simple_tape_barcodes.pl

Also contributed by Toivo Pedaste. It can be used to keep afbackup tape numbering according to tape labels readable by a changer device. The last two digits of the labels are used to reflect the afbackup label numbers. This is not a really general solution, but might be sufficient for some installations. In most cases it will be necessary to review and modify some variable settings in the first few lines of the script. Unfortunately Mr. Pedaste did not tell us how to use the script in the configuration, but most likely it should be configured as SetCartridgeCommand

  • Webadmin-Module

Dirk Wallmeier is developping a module for webadmin. The project homepage is http://sourceforge.net/projects/afbackup-webmin . I have no experience with webadmin and the security impacts or considerations of that software. Thus i can only tell it exists and might be helpful, but can't give any recommendation.

THANKS TO

(in chronological order)
- The people at "Zentrum fuer Neuroinformatik" for being so kind in letting me put this into the PD. - Rick Macdougall at Axess Communications for reviewing my bad English. (A lot of text has been added up to now, he had no chance to review it - so it's my fault, if there is a lot of nonsense)
- Lars Koeller at the University of Bielefeld, Germany, for doing the FreeBSD-port and giving me some important hints. - Christian Meder at the University of Stuttgart, Germany, for bug reports, fixes, making the whole package autoconfig- -urable and Debian-ready, extracting the man-pages and a lot more
- Ivan N. Kokshaysky at the Moscow State University for making afbackup libc-6 (ie. glibc) - ready
- Katharina Hoffman at Infomedia GmbH for doing a lot of tests - GianPiero Puccioni (gip@ino.it) at "Istituto Nazionale di Ottica" in Firenze for doing a lot of testing and problem determination, furthermore contributing the mtx.c program for using DAT autochangers, all on HP-UX.
- Tuomo Soini (tis@foobar.fi) for 'feature' fixing - Andreas Wehler at CAD/CAM Straessle GmbH in Düsseldorf/Germany for intensive testing and helpful suggestions - Scott C. Ostrander and Dave Williams for proof-reading and correcting the documentation texts
- Piotr Klaban in Torun, Poland for numerous hints, suggestions and bug fixes (sometimes i have the suspicion he knows my software better than me)
- Jerome Lovy for helping to track down the truncated files problem (to different behaviour or zlib-s) making zlib use more robust - Toivo Pedaste for several helpful hints - Many thanks for "Lele Gaifax" for implementing the I18N/L10N gettext stuff and translating all the messages to Italian - Jalon Q. Zimmerman at "coldworld" for setting up, hosting and sponsoring the afbackup.org domain, website and mailing lists - Ken R. (?) for some English fixes in the documentation - Stefan Scholl at Infineon Technologies for a concept to start programs remotely without having login permission to a host - Oliver Hartmann, Mainz for contributing the chio changer config - Johann Pfefferl, Munich for contributing the sch/mover config - Peter 'Rattercrash' Backes for adding the disable threads option and other improvements and suggestions - Mr. Neil Darlow for a LOT of useful hints concerning FreeBSD, IDE tapes and more
- Devin Reade for reviewing large parts of the code - Torsten Werner at Auswärtiges Amt, Berlin (earlier at the Dresden University of Technology, Germany), for adopting the maintenance of the afbackup Debian package, several hints, fixes and continuous support
- Dan Debertin for porting to NetBSD
- Rudolf Cejka at Brno University of Technology for enhancements and UnixWare fixes
- Vlad Solopchenko for a bug fix
- Jeannot Langlois for the uninstall targets in the Makefile


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