first of all, we use a different storage method with mysql and Barracuda. The method is optimized for blob storage.
Second, we store a log about all database operations. This log can be used to rebuild a database from scratch or partial.
Third, we have a triple backup concept. That means, beneath the main storage we have 2 mirrored copies of the main database.
Fourth, we store the last 10 OAR-files from our mainlands and the rented regions on different servers. For region tenents we also produce abd store IAR files. OAR for rented regions are produced automaticly and will be stored for the last 10 days.
Fifth, everyone (also without any own region) can produce and download an IAR backup with our IAR-Manager: http://manager.hypergrid.org/IAR
There is also a function to import an IAR file.
But be patient: The OpenSim software is very buggy and unsafe. Your datas are not realy safe!
It could be, that the IAR or OAR could not be imported. And thats the worst, when your backups are in error and can not be used.
We suggest to install a "Sim on a Stick" as a quick OpenSim standalone version as a test-version. Then import an IAR and OAR file from time to time. Verify afterwards, that everything was imported. If so, you can lay back. You are excellent prepared for any crash and nothing can happen to you.