BatFlattery

John Gruber’s recent hard disk failure, combined with some travel plans that I have, made me realise that I need to improve my backup strategy. I currently have a 500Gb Iomega FireWire external hard drive permanently connected to my iMac, so that Time Machine can do its backups. But as Gruber points out, you can’t just boot from your Time Machine drive in the case of catastrophic disk failure: you need a bootable backup disk. I was also worried that if something happened to my iMac while I was away, such as theft or destruction by fire, the Iomega might be lost as well.

So I decided to buy a new external drive and back it up with SuperDuper, which I have used before. The great thing about SuperDuper is that it comes in a free version that you can use to create complete, bootable backups of your main drive (the paid version lets you do incremental backups, whereas the free version erases the backup drive each time, so it takes much longer to do regular backups).

I looked on Amazon for a nice external drive. All of my external drives to date have been the large, powered ones, because they are generally cheaper, and also faster; but finding yet another socket on the power strip for one more wasn’t something I relished. Since I only intended to use it for periodic backups, relying on Time Machine for my day-to-day backups, and since prices seem to have declined, I decided on a Seagate 500Gb portable drive, the Seagate 500gb Expansion External Portable Usb 2.0 Hard Drive. It is a portable drive, entirely powered by the USB cable, and costs about £70.

It arrived from Amazon this morning, and I was somewhat alarmed to see all the Windows compatibility stickers all over it, with no mention of Macs. On opening the box I found a really small and light drive, not much bigger than an iPhone. Plugged into the iMac, it was attached in the Finder, and showed a few files, including an Autorun file, and a Seagate folder containing some junk.

First problem came when trying to delete these files; the Finder couldn’t do it. I fired up Disk Utility and saw that it was formatted as an NTFS drive, not a total surprise as that is the latest Windows file system! So I just reformatted the drive as Mac OS Extended (Journaled), and proceeded to do the backup on SuperDuper.

The tradeoff with the external power supply soon became apparent; the drive is not very fast, and backing up 136Gb took a couple of hours. The next annoying thing happened when I tried to set the drive as the boot volume, to test the backup by actually booting from it. The drive did not appear in the selection window.

A quick scan of the SuperDuper help site revealed a possible problem: OS X under Intel can boot from USB drives (unlike PowerPC Macs) but not if the disk is partitioned using Master Boot Record (MBR). A quick check with Disk Utility showed that the disk was indeed so partitioned (and why wouldn’t it be?). Aaargh!

So if you’re going to use this little drive as a SuperDuper bootable backup, remember to repartition the drive itself, and don’t just reformat the volume.

Finally, some wise words from Gruber:

Hard drives are fragile. Read as much as you can bear to about how they work, how incredibly precisely they must operate in order to cram so many bits onto such small disks. It’s a miracle to me that they work at all. Every hard drive in the world will eventually fail. Assume that yours are all on the cusp of failure at all times. It’s good to be spooked about how long your hard drives will last.

Make sure you are prepared for when yours goes phut. Not if. When.