Take Control of Mac OS X Backups: Part Two
Sidebar: Backing Up iTunes Music Store Purchases
Audio tracks you’ve purchased from the iTunes Music Store (iTMS) differ from tracks you’ve imported from CDs you own. Besides the fact that with downloaded files you don’t have an original copy to serve as an extra backup, the iTMS tracks, which are encoded as AAC files, include special copy protection to ensure that they can only be played by the purchaser, and only on one of up to five authorized computers. Because iTMS tracks are especially valuable, you should take extra steps to protect them:
• Always include iTMS tracks in your archive backups. If you import tracks from CDs as MP3 files, you can use your backup software’s exclusion feature to filter out all MP3 files while keeping the AAC files.
• Be sure to include the /Users/Shared folder in your archive backups as well; this folder contains hidden information required to enable authorization.
• If you suffer a severe crash and decide to erase your hard disk (in order to restore all your data from a backup), deauthorize your computer first. To do this, open iTunes and choose Advanced: Deauthorize Computer. Choose Deauthorize Computer for Apple Account, and click OK. After restoring your backup, re-authorize the computer by opening iTunes and choosing Advanced: Authorize Computer.
Sidebar: Remote Backups
In the discussion so far, I’ve assumed that the machines you need to back up are connected to the same local network as your backup server. But what if you travel frequently with a PowerBook or iBook? Can you use a broadband connection at a hotel or cybercafe to copy the files to your server over the Internet? The short answer is: Maybe.
“Push” backups work only if you can mount your backup server’s volumes remotely; “pull” backups work only if your server can mount your laptop’s volume remotely. Sometimes this works, but often not— your firewall at home must enable access to the necessary ports, and the ISP providing your remote access must also permit file-sharing access over their network. You also run a certain risk that your files may be intercepted in transit by a hacker, unless you take extra steps to encrypt the network link between your laptop and your server.
Client-server backup software, such as Retrospect, normally polls only the local network for available clients. In some cases—for example, with the more-expensive Retrospect Workgroup or Retrospect Server packages—you can manually enter an IP address for a computer outside your local network. However, if you’re traveling and don’t know what IP address you’ll have at any given time, this method is problematic. One possible solution is to use a dynamic DNS service, such as the one provided by easyDNS, to assign your laptop a domain name whose IP address changes as needed, and then enter that domain name in Retrospect.
This problem is more readily solvable using a VPN (virtual private network) connection to your home network, but the details of setting up such a system go beyond what I can cover in this article. As a lower-tech workaround, consider packing some DVD-R media for temporary backups when you’re on the road—and be sure to store the discs separately from your laptop!