I my Aperture library is just a little north of 800GB in size on a 1TB LaCie FW 800 HD (primary). My previous backup strategy was to copy the library via a spare Mac Server via 1 GB ethernet to a 36TB Isilon NAS and then copy this back to an identical 1 TB LaCie (backup). This gave me three backups in three locations.
This worked fine and only took about 4 to 5 hours to backup the primary disk to the Isilon and I didn't care how long it took to make the LaCie backup.
Once I hit 800 GB the time to backup the drive to the Isilon started to get in the range of 12 to 14 hours with more than a 1/2 million files being copied.
Obviously this isn't working from an efficiency standpoint and I need to come up with a better backup plan one thats reasonably easy to use and faster to get done without sacrificing security of multiple backups in multiple locations.
Pro, OS X Mountain Lion (10.8.2), 16GB SDRAM