Data redundancy (RAID mirror)
Today diglloyd.com was down briefly while the server was moved. When it rebooted, one of the hard drives did not spin up, simulating a disk failure. Fortunately, the hard disk hadn’t actually failed, rather it was a cabling issue. And even better, the diglloyd.com web server runs on a 2-drive mirrored volume so that failure of one hard disk won’t take the site down.
Mac OS X has built-in support for mirrored volumes. Seen below is the progress shown while Disk Utility rebuilds the errant disk partition. (“Degraded” means that one or more disks have failed). For even more protection against disk failures, a mirrored volume could use more than the minimum of two disks, but barring an Act of Dog that might ruin all the disks at once, odds of two hard drives failing within a few days of each other is rather small, so two disks should suffice for most uses.
I’ll have much more to say on the subject of storage in the future. But in particular, Mac Pro users with empty drive bays might find that a mirrored volume offers simple yet highly effective protection against disk failure. Setting up a mirrored volume is easy, and one can even boot from it, offering protection for both the system and its data.