nnfs2 [--no-x11] {--add-first dir-name | --add dir-name | --add-nickname dir-name}
nnfs2 {--help | --licence}
The NNFS goal is to provide to one user a consistent file system over all the hosts used by the user.
With hosts connected on a LAN you must use NFS instead of NNFS. In the case of hosts not connected by a network or connected by a slow network (modem) NFS is not the answer.
With NNFS, the files are duplicated on all the computers. The up to date files are on the computer on which the user works. The FS is stored on the MEDIUM. Usually the MEDIUM is a floppy disk, it could be whatever you want (easily customisable), if there is much data, several floppies will be asked.
When the user stops his work on a computer, he runs as last command: NNFS. Then all his modifications (change, creation, deletion) are recorded on the MEDIUM.
When the user starts to work on a computer, he runs as first command: NNFS. Then all modifications (change, creation, deletion) stored on the MEDIUM are retrieved on current system.
If the user forgot to run an update, NNFS will nevertheless optimally work. The only drawback is that some files will not be up to date on the host used by the user.
It is also possible to have a numbered backup of modified/deleted files. So you cannot lose a file when you run NNFS (because the file is modified/deleted on another host)
NNFS has a text and a graphical user interface. If you run the command for the first time or with a MEDIUM formatted or not, the command will provide contextual informations and help and will ask contextual questions. The graphical user interface allows you to edit the configuration.
The interactive help is extensive and guide the user. This documentation is here to give general principles.
By default NNFS works with standards tools: floppy disk and gzip. The floppy disk access is done via system dependent commands (IRIX, AIX, HPUX and mcopy in the other cases). If you want to change these defaults, see the configuration section.
As the default configurations use floppy disk, the NNFS default filter does not synchronise big files or garbage files. If you want to change these defaults, see the configuration section.
It is not recommended to continue to modify files while NNFS is running. It is not dangerous but the result is unpredictable.
Be carefull, some applications wrote their data on disk only when you stop them. So you must stop these applications before running NNFS. For example firefox wrote some folder information only when you quit the program, so you must run NNFS only if firefox is not running. To avoid this you can create a shell script killing these applications and cleaning some file before launching NNFS.
If the file hierarchy you want to synchronise is yet identical on all the hosts you can go to the next section. The root of the file hierarchy may have a different name on each host. To avoid problems you should use only relative internal symbolic links, so the links are correct on all the hosts.
If the files hierarchy are not identical, you have two solutions:
When you run the NNFS command on an host not known by the FS it will explain you how to add the host in the FS.
If the FS does not fit in one medium, you will be asked to introduce a new medium.
Now, the initialisation for 2 hosts named A and B will be detailed for the 2 user interfaces.
First run on host A.
Second run on host B, assuming medium is ready.
Normal run when initialisations are done,
First run on host A.
Second run on host B, assuming medium is ready.
Normal run when initialisations are done, assuming medium is ready.
If there is a read error you can rerun NNFS a few times with the hope that the error will vanish. If it is not the case, put the bad medium in a trash, take a new one and create immediately a new FS with the current host.
If the read error is before you start to work on an host. Try to not work on non-synchronized file in order to avoid future conflicts. Run NNFS as always before stopping to work on the host.
If the read error is before you leave an host. You will want to copy the file modified by your session on the other host. To do so, modify all the file you want to synchronise and rerun NNFS on the host. For example by running find . -mtime -1 -print | xargs touch. If you do not do this, these files will be synchronised but only after adding the other host on FS, a run on local the host and a run on the other host.
My experience about floppies is that there is floppies usable only 2 or 3 times and some usable hundreds of time. Even if they are from the same computer.
Each time you run NNFS the files deleted or modified are moved in a directory. This history directory is not mirrored!
Current date: Sun Sep 16 14:57:47 CEST 2001
Modified file: foo/bar/Makefile
Historised file: .nnfs/history/2001_09/16_14:57.47/foo/bar/Makefile
So you can easily remove old historised files by date.
If you don't run NNFS before and after working, some update conflicts may be raised if you work on the same files.
The conflict solving method is straightforward, the remote conflicting file is always copied on local host. If you don't agree, you can retrieve the local file content from the .nnfs/history directory.
This method is not used to solve conflict when adding a new host. In this case, the most recent file is copied over the old ones
If you run NNFS on several hosts using NNFS, you must indicate to NNFS that the hosts use the same file system.
The mirrored directory must have the same name on all aliased host Assuming that the medium is ready, adding an alias with X11 interface.
Assuming that the medium is ready, adding an alias with text interface.
The configuration file is .nnfs/nnfsrc, it is created the first time you run NNFS. It is a hugely commented shell script you can edit. It is a shell script to allow some default values to be computed from the system.
If you find this configuration file too complex to edit, you can use the NNFS X11 interface to edit the file. There is many tips to help you configure.
The more useful options are :
The option hard to configure is OUTPUT_FILTER. The default value is fine for me but certainly not for you. The minimal filter must stop the copy of NNFS history and all backup files.
-regex=~$ -regex=^\.nnfs/history/
But, to run NNFS you must be connected, and the connection modify some file you don't want to copy on other hosts because it is a security breach or it is a non-sense. For example, any dot file in connection directory ending by history or authority
-regex=^\.[^/]*(history|authority)$
If the medium is small, you need to filter the files that are garbage as core, the executable files or the results of compilation as .o files. I assume here that executables biggers than 50k are not scripts shell or perl.
-type=f size=+50k perm=+111 -regex=(\.(o|a|so|sl|aux|log|dvi|summary|old)|/(core|a\.out))$
The big shell or perl script are filtered, if you don't want this. Tell NNFS to not filter them.
+regex=\.(pl|sh|tcl)$ +regex=/configure$
Each line starts by - or +, to remove or add to the file set the files verifying all the conditions in the line.
The conditions are:
If you want to synchonise the files with there UID and GID you need to be root and to run rootnnfs2.
Limitations:
Bugs:
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
It is nearly impossible that NNFS do an irrecoverable error. In the worst case, NNFS will stop. The returned value (error) of all the system calls are verified and the program tries to analyse the error. The parameters of the more stressing test on NNFS are the following: 4 hosts
On each host a program create/delete/modify file/links/directories at the maximum speed.
NNFS runs continuously on each of the host randomly. So, while NNFS runs, files are modified while it is reading/writing them. Or worstly, directories are deleted while NNFS analyse the content, or files are created in directories that NNFS tries to delete
Incredibly, NNFS works in this case thousands of time on a Linux 386 Debian host.
NNFS had been compiled and tested on HPPA 1.1 HPUX 10.20 and MIPS IP30 IRIX 6.5
On Mac OS X it does not work optimaly with symbolic links (see BUGS).
Author: Thierry EXCOFFIER, Author Home Page: http://perso.univ-lyon1.fr/thierry.excoffier/
NNFS home page: http://perso.univ-lyon1.fr/thierry.excoffier/nnfs.html