Time Machine is one of the big new features of Leopard, not only due to the simplicity of making a back-up, but also from the point of view of recovering files that have been deleted or modified since the original back-up. Using an external disk, USB or Firewire, this back-up proves to be simple and comfortable - one only has to remember to connect the disk regularly. Following the concept of the Time Capsule it is now possible to use Time Machine with an external disk connected to an Airport BAse Station N. On paper this is a very elegant solution. It is just necessary to connect to the network and everything is done behind the scenes with any user intervention. However in reality, this solution is not so tempting. Since, most of us, maybe all, have several tens of GB of data on their disks, and sometimes several hundred, shared among hundreds of thousands of files. Using WiFi, the backup to a Time Capsule disk (or to a disk connected to an Airport base station N) is very slow. Our tests have shown that in optimal conditions, with the computer close to the base station running 802.11 n on the 5 GHz band one can reach the famous 300 Mbits.s; however the write speed to the disk never exceeds 5 to 6 MB/s. For those who are not so close and thus the conditions are not optimal the speed reduces to 2 or 3 MB/s. This is the fastest speed obtained with large files, while with smaller files the speed is further reduced. In this case the first back-up can take most of a day, and the incremental back-ups can take over an hour if some substantial software has been installed or a big file has been modified or if a new full back-up is needed. Here are some tips to limit the time needed for a backup: - Get as close as possible to the basestation, and if possible you can connect via Ethernet, especially for the first back up. - Think about excluding temporary files that are without interest. - if you share photos or music over several machine: exclude these on the secondary machines. - Remember to exclude all external disks that you connect to your computer. - if you often download files, think about excluding the download files from the back-up, and why not the desktop that is often used as a temporary work buffer? Doing this - the back ups become quicker and more efficient. [translation by crispin]

	Read more at Mac Bidouille
	www.hardmac.com/news/2008-03-22/#7990