The importance of external bootable backups

This morning I posted an article about some CrashPlan-related issues discovered when migrating my wife’s dead iMac to a new machine. Another lesson learned in that situation was about the importance of external bootable backups.

My wife’s old iMac, dating back to 2011 I believe, had an internal 256GB SSD and a 1TB internal hard drive. Back in the day, I thought I could improve her desktop tidiness by doing without an external drive, and creating a 256GB partition on that 1TB drive, for the purpose of maintaining a bootable backup.

What I didn’t consider at the time is what actually happened last week—green bars suddenly appeared on her screen, followed by a shaking and shifting of the image, increasing in frequency until the whole screen went white—and the machine shut down. And then upon reboot, the whole ordeal would start again!

Evidently the machine was dying, and it occurred to me then that the only bootable mirror I had for migrating to a new Mac was the hard drive inside that dying iMac!

Since the bulk of the computer’s files lived on the other portion of the 1TB drive, managed by BitTorrent Sync, the start drive itself contained relatively little data. So I had hopes that I could keep the machine booted long enough for Carbon Copy Cloner to mirror the startup drive to an external USB drive. Lucky for me, after a third reboot, the machine stayed up long enough—barely!—for CCC to finish its backup. The machine repeated its meltdown literally seconds after the backup completed.

Lesson learned: Always maintain an external bootable backup of important machines!

Agree? Disagree? What do you think?