Group Aufs Protocol

Last revision July 19, 2004

The system administrator can set up Aufs directories with group write permissions to facilitate collaboration on projects. When done, each person can modify, delete, or create Macintosh files on this volume. Therefore, you have to worry about two different accounts attempting to update the same file at the same time. To avoid this problem, and provide a backup in case you corrupt the file data (this has happened in the past with shared Macintosh volumes) use the suggested file access protocol:

1. Before editing an existing file, check to see if anyone else is already working on it. The presence of a copy of the file with the suffix Copy indicates that someone else is already working on making changes to the file. Contact him/her to coordinate your changes.
2. If no one else is currently working on the file, first duplicate the file in the same folder, which will automatically add the suffix Copy to the name. For example, if you want to update the file Data Spreadsheet, first duplicate it to make Data Spreadsheet Copy
3. Make your changes to the Copy file, NOT to the original. Please note that, because the pangea Aufs AppleShare server is based on a public domain software running on Unix, it does not implement all features of a "real" AppleShare server on a Macintosh, and some programs cannot reliably edit a file "in place" on the pangea Aufs volume. To use such programs, you have to copy (drag) the file down to your Macintosh hard disk, work on it there, and then copy (drag) it back. Programs with this problem include SimpleText and FileMaker Pro. Some of the newest versions of Microsoft Word or Excel might also have problems.
4. When ready to install your changed version, first rename the old one with a Old suffix, and then rename your new one to the original name. For example, change the name of Data Spreadsheet to be Data Spreadsheet Old, and then change the name of your new updated version from Data Spreadsheet Copy to simply Data Spreadsheet.

Besides providing a mechanism to signal others that you are working on the file, and thus prevent them from trying to make simultaneous upgrades (which will corrupt the file), this protocol also insures that you always keep the most recent previous version (the Old copy) as a backup in case the file is corrupted.

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