I use VMWare Fusion on Mac OS X and backup my system with Time Machine. Now I read, that this will not backup my virtual machine with usable results. What are my possibilities to back up my virtual machine?
Time Machine works by tracking changes to files and saving a copy whenever they change.
This doesn't work with VMWare Fusion because a VM image file is all-in-one, so any change within the VM - just running the VM changes the file - will change it, causing Time Machine to have to save another copy of the VM image.
You can manually backup VMWare images just by copying them somewhere safe, like an external drive.
VMware Fusion disk files are either a single large file or many small 2GB files. When your virtual machine is running, any change to any of these big files causes Time Machine to backup the entire set. So, you can let Time Machine backup the disk files, but every backup will be really really big, which will fill up the space of your Time Machine disk very quickly.
To get around this, I rsync my virtual machines to a separate drive every so often. To do this:
The first backup will be a long copy, future backups will go a little bit faster. You will not end up with a Time Machine-style history, but just a complete copy of the virtual machine as of your last backup.