You have choices when you want to re-use, recycle or destroy a hard drive. Let’s look at a few common scenarios.

You have a computer that you want to retire or give to somebody else.

In this situation, the hard drive works properly. You just want to securely erase your data before giving the computer to another person. Thus, you want to securely erase the hard drive and then reinstall Mac OS X. Follow the instructions in my previous Tech Tip article on how to securely erase a hard drive. If you don’t want to do this work yourself, you could take your computer to an organization like Interconnection or Total Reclaim. Both of these organizations offer free data wiping of all hard drives on donated computers. I tend to use Interconnection as much as possible since they are a non-profit group that does their best to re-use the computer, while Total Reclaim is a for-profit company which focuses on recycling computers and other electronics.

You have an external hard drive that you want to re-use or sell, but first you want to remove all of your personal data from it.

This is very similar to the first situation. The hard drive works properly and you want to re-use the hard drive. Thus, you should securely erase the data from the hard drive using the instructions in my previous Tech Tip.

You have a hard drive that died and you need to get rid of it, but want to make sure that nobody can ever get any of the data.

Since the hard drive is not working properly, we can’t securely erase the hard drive as described above. Instead, the hard drive will need to be destroyed. You could either do this yourself or have somebody else do it. If you want to do it yourself, you could secure the drive in a drill press and drill a few holes through it. This would destroy the circuit boards and, most importantly, the platters containing your data. If you want somebody else to destroy it then I recommend using an organization like Interconnection or Total Reclaim.

Here are instructions on how to use Disk Utility to securely erase a hard drive connected internally or externally to your Mac. These instructions were written for Mac OS X 10.4 to 10.6. The process is very similar on older versions of Mac OS X but the screens will look a bit different.

Requirements – You’ll need either the Mac OS X install disk that came with your Mac or another OS X install disk that’ll boot your Mac, such as a retail copy of the Mac OS X 10.5 or 10.6 install disk.

I recommend securely erasing a hard drive before you recycle it or give it away. The instructions below include the option to re-install Mac OS X onto the hard drive at the end of the process.

If you’re securely erasing an external hard drive you do not need to use a Mac OS X install disk. Instead, you can simply open Disk Utility which you’ll find in the Utilities folder inside the Applications folder. In Disk Utility, select the external hard drive and then follow the last few steps of these instructions to erase it using one of the Security Options described below.

Background – Technically, it’s not possible to erase or remove data from hard drives. Thus “securely erasing” is a misnomer. Instead, what we’ll be doing is over-writing the data on your hard drive with gibberish, a random string of bits of data. When you securely erase your hard drive you’ll have a choice of how much over-writing you want to do. This process can take many hours if you select the 7-pass overwrite procedure. I recommend starting this process and then letting it run over-night.

• Insert the Mac OS X install disc that came with your Mac.
• Note: The disc will begin the process of installing Mac OS X on your Mac. Whether or not you actually choose to install Mac OS X is your choice, but if you do, you’ll do it AFTER you’ve securely erased your Mac’s hard drive.
• Select your preferred language from the list presented.
• When you see the welcome screen for the Mac OS X Installer, go to the menu named Utilities and select Disk Utility.
• In the left pane of the Disk Utility window, click on the hard drive you want to erase.
• In the right pane of the Disk Utility window, click the Erase tab.
• Click the Security Options button.
• I recommend that you select the 7-Pass Erase options, but you could choose the 35-Pass Erase option. Here’s my description of these options.

Don’t Erase Data— This option does not provide any security. This option only over-writes the directories on the hard drive. Your files could still be recovered.
Zero Out Data— Provides a pretty good level of security. All of your files are over-written with a string of zeroes. There are forensics utilities that in theory could retrieve some data.
7-Pass Erase— Provides a lot of security. This is considered sufficient by government standards to erase data from a disk. It writes a random string of ones and zeroes over your data files seven times. It may take several hours or more to complete this process.
35-Pass Erase— Provides the maximum amount of security offered. This option takes an extremely long time, possibly more than one day.

• Click the radio button in front of 7-Pass Erase.
• Click OK.
• Click the Erase button next to the Security Options button.
• Confirm you want to erase and the process will be begin.
• If you want to install Mac OS X then go to the Disk Utility menu and select Quit after the erase is complete.
• You’ll be taken back to the Mac OS X Installer welcome window. Click Continue.
• Agree to the software license.
• In the “Select a Destination” window click on the icon for the hard drive which you just erased and then click Continue.
• Click the Install button to start the installation process. Depending upon the speed of your Mac and the version of Mac OS X which you are installing this process could commonly take anywhere from 20-60 minutes.

Did you know that you can remotely find and/or erase your iPhone? You can if you have a MobileMe subscription and have the Find My iPhone feature turned on.

[Update February 2013: Apple has now made Find My iPhone a part of the free iCloud service. The rest of this tip has been updated with the correct terminology and directions.]

First, let’s enable this feature on your iPhone. Turn on your iPhone and go to Settings. Go to the iCloud section, then turn on the Find My iPhone feature using the slider button.

Now, let’s test this feature. Go to http://www.icloud.com and login to your iCloud account. Click the green Find My iPhone button on the second row of icons. You’ll be asked to enter your iCloud password a second time. Apple is just being extra secure by asking for this information.

Wait a minute or so while your iPhone is located. I should mention that this service relies on the GPS chip in your iPhone so if the iPhone is off then this won’t work. A map showing the approximate location of your iPhone will appear. This can help you determine if your iPhone is around the house, at your office or if you forgot it at the restaurant last night.

Below the map you’ll see three buttons: Display a Message, Remote Lock and Remote Wipe.

Display a Message lets you display a short text message on the screen and play an optional alert sound. This sound will play even if the phone is in silent mode. This sound can help you find the phone if it is under a couch cushion. Or it could help a waiter find it if the phone is under a restaurant table.

The Remote Lock feature lets you enable the lock so nobody can view your data or run-up your phone bill. In my last blog article I recommended that you enable the lock feature on your phone  all the time.

The Remote Wipe feature allows you to remotely remove all data from the phone. As long as you have synced your iPhone recently, then go ahead and do this. If you locate your phone eventually then you can restore all of the data by syncing it to your Mac.