There are three ways to backup your Gallery. They are both described here.
There are some caveats to backing up your albums! Please read the caveats section for more information.
Backup using tar is relatively simple, but you must have shell access. Run the following command in the parent directory of your albums directory:
tar -czvf albums.tar.gz albums
This will give you a file, albums.tar.gz which contains your albums directory.
Basically, to backup your albums using FTP, just download the whole albums directory. This will give you an exact copy of the directory on your local computer, which you can hold on to in case it's needed
To restore your albums directory using FTP, just re-upload the albums directory that you downloaded to your computer. The only problem is that the new files MUST BE CHMODDED 0777 RECURSIVELY. Recursively means every file and every directory. This can be a pain using FTP, but is necessary or you will recieve errors.
Gallery 1.3.4 is equipped with a new backup_albums.php script to backup your albums. It's located in your setup/ directory. To use it, you must copy it out of the setup/ directory and put it in your base gallery directory.
Then navigate to it using your browser, when logged in as an admin. For example, http://www.example.com/gallery/backup_albums.php. From there you will have a number of options.
Using the "All Files" option will more than likely give a HUGE file, and may take a while. We recommend just backing up the data files.
WINDOWS USERS -- It is recommended that you just use WinZip or FTP to backup your files because most Windows servers don't have any of the utilities that the backup script needs.
When backing up on one platform and trying to restore on another platform, i.e. transmogrify from Windows to UNIX, you will need to eliminate all occuring "\r" (LF) in all the .dat files. Double-Breaks like "\r\n" will have to change to "\n". Utilities like dos2unix and can help in this realm.
If you move your data files between Windows and Unix, your user database will not work properly. You'll have to manually rebuild your user database. Hopefully this will be fixed in a future Gallery version.