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Recovering from a catastrophic drive failure. System
I can't say it enough. Back up your hard drive. I'm going to talk here about what I recommend as the best way to protect yourself from a catastrophic hard drive failure. Keep in mind that what follows is just one of many ways to protect your Mac.

This will cost you. You need to purchase an external hard drive to use with Time Machine. When your internal hard drive fails, you will then need another external hard drive to restore to from Time Machine. You will be using that new external hard drive to work from until you're ready to repair your Mac.

The Time Machine basics:

The size needed for this hard drive depends on how much space you expect to use on your internal hard drive. If you're currently using only about 30GB of your 500GB hard drive and you don't expect to be adding a lot of videos or photos in the future, then you can safely use a 120GB hard drive. In other words, your Time Machine backup drive should be about three times the size of what is being used in your internal drive. You need the extra size because the Time Machine keeps a running history of all the changes you make.

If you want to be able to go back in time by several months to recover a lost file or an older version of a file, you need the extra size. If all you want to do is keep a few days or a few weeks of older versions then an external drive a little larger than what you currently use would be sufficient and save you money. For example, to back up 30GB, use a 80GB hard drive. Good luck finding one that small.

When the Time Machine is disk gets full it just removes the oldest backup to make room for the new backup. Hence, the smaller the external hard drive, the less history you can save. It should be noted that if the Time Machine disk is small, it will need to frequently delete an older backup to make room for a new one, and that takes more time.

The interface for the Time Machine disk can be USB 2.0 or Firewire 400 or Firewire 800. If you don't mind that it takes a long time to perform a backup (many minutes instead of a few minutes) then use USB. Time Machine works in the background. Still, when it does run, it requires computer resources. If you don't like being slowed down a little while Time Machine is running (about every hour), then find a hard drive with a Firewire 400 or Firewire 800 interface (800 is faster than 400) - and be prepared to pay a lot more. Alternatively, turn off Time Machine when you are using the Mac and turn it back on when you're away from your Mac (the Mac has to be on and not asleep for Time Machine to work; the display can sleep, but not the computer).

Here are Apple's instructions for setting up Time Machine. The type of interface to choose for the new external hard drive you intend to use as a temporary startup disk is up to you.

Recovering from a failed internal hard drive:

This is rather simple.
  • Make sure your Time Machine disk is connected and turned on.
  • Connect a new external hard drive to the computer and turn it on (same size or larger as the internal drive).
  • Insert your Mac OS X Install media in the CD/DVD drive.
  • Hold down the C key when you press the power button. The computer will boot up from the install media in the CD drive.
  • When the Language Chooser appears, select your language, and then click the Continue button.
  • In the Installer, choose Utilities » Restore System From Backup.
  • Select the Time Machine disk and click Continue.
  • Select the latest backup from the Time Machine disk.
  • Follow the onscreen instructions to select the new external hard drive to restore to.
  • Be patient while the restore takes place.
What if you can't find your Mac OS X Install media? Then you will need a clone of your internal hard drive to boot up from. See how to create one here. But be sure to do that before your internal drive fails.

If you used a clone instead of the Install media to boot up from, you only need to restore everything from the latest backup of the Time Machine to the clone. Do that after you boot up from the clone the first time.

Booting up from the new external hard drive:
  • Hold down the Option key while you press the power button and keep it held down until the Start Up Manager appears.
  • When the Start Up Manager appears, select the new external hard drive to boot from.
  • When the computer is up and running, open the System Preferences.
  • Select the Startup Disk icon in the fourth row of icons.
  • From the available disks showing, select the new external hard drive as your new system startup media.
  • Restart the Mac.
  • Each time now that you start up the Mac, it will boot from the external drive without having to do anything special.
You are now ready to use your Mac as though nothing happened. But don't forget to turn in your Time Machine disk with the computer (you won't need to also turn in your new external hard drive) when you are ready to have the internal hard drive replaced. Make sure you force a backup on the Time Machine just before turning off the Mac. The repair center will use the Time Machine disk to restore to the new internal hard drive.

Play safe so your Mac won't disappoint you. You can print out this note for future use.

[crarko adds: OK, this is not groundbreaking news to those of us who have been supporting Macs for a while, but once again for the benefit of the newer users it's nice to have step-by-step guides. I've had to do this kind of recovery for Windows desktops and servers and I once again marvel at how fortunate we are to be using Macs.]
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Recovering from a catastrophic drive failure.
Authored by: deemery on Apr 26, '11 08:24:46AM

Apple strongly discourages (or maybe even prohibits now) using a bootable drive for TimeMachine. So when thinking about backup, the best thing to do with a new external backup drive is (a) partition it allocating a 20gb partition for the OS and the remainder of the drive for TimeMachine; (b) install the OS onto that 20gb partition (and then running all the updates against that partition.) I've found that you need to have at least 10gb of free space on a bootable partition after installing Mac OS X if you want to be able to easily run Software Update - those updates often require 5-7gb of free space on the drive to install.

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Recovering from a catastrophic drive failure.
Authored by: markuswarren on Apr 26, '11 09:57:27AM

I could be, and am probably wrong, however I have some niggling feeling that you need to make sure that the restore / install DVD you use when restoring the TM backup is the same version of OS X that the machine was running, otherwise you cannot restore. The example being; the machine shipped with 10.5, and so has an install DVD with 10.5.x on it. You have since upgraded to 10.6.x and thus the TM backup is based on 10.6. If you boot from your 10.5 install DVD, then you might find you cannot restore.

As said, I might be wrong on this point, but if not, it is something well worth updating the hint to mention.

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Recovering from a catastrophic drive failure.
Authored by: TrumpetPower! on Apr 26, '11 11:24:01AM

May I suggest?

Rather than a drive physically attached to the computer you're trying to protect, use a drive that's at least in another part of the house. Many things that're likely to cause you to want to use your backup will take out all devices attached to the computer, not just one of several internal components.

I've got an ioSafe hooked up to an airport in a closet on the other side of the house. The ioSafe is fireproof and waterproof. It's on a completely different electrical circuit.

It's far from foolproof, but if anything took out my setup, recovering data would be the least of my worries.

If I were really especially paranoid, I'd supplement my setup with a pair of portable hard drives. One would be attached to the computer and also be a TimeMachine backup device. Each week, I'd take it to the bank and swap it with its twin in the safe deposit box. But I'm nowhere near that paranoid nor interested in spending that kind of time and money, so I don't.



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Recovering from a catastrophic drive failure.
Authored by: wallybear on Apr 26, '11 01:54:09PM

Two little things to note:

1) "The type of interface to choose for the new external hard drive you intend to use as a temporary startup disk is up to you."

This is not exact: some non-intel Macs cannot boot from USB drives.Check if your model can, before buying an USB external HD; otherwise choose a Firewire drive (400 or 800).

2) It's a good habit to use the Time Machine preference pane to exclude from TM backups your download folder, as its contents change very often: if you downloaded something that you really want to keep you surely will move it from that folder, so TM will backup it from its final destination.

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Recovering from a catastrophic drive failure.
Authored by: johnnym on Apr 26, '11 02:06:58PM

I was going to post a step-by-step guide on using TM but thanks to this great post, I don't have to. :-) Couple of things I'd like to add:

- If you're on a MB/MBP, you can set TM to not do backups when you are not connected to AC power.

- If you don't want TM to backup every hour and want to control when you do backups, Snow Leopard allows you to turn off TM backups in System Preferences and do on-demand backups by clicking on the TM icon in the menu bar and selecting "Back Up Now".

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