Backing Up and Restoring Your Data - Beyond the Basics - Macs All-in-One For Dummies, 4th Edition (2014)

Macs All-in-One For Dummies, 4th Edition (2014)

Book III. Beyond the Basics


image Check out the article “Finding and Adding Fonts to Your Mac” online at

Contents at a Glance

Chapter 1: Backing Up and Restoring Your Data

Chapter 2: Protecting Your Mac against Local and Remote Threats

Chapter 3: Networking Your Mac and Connecting Peripherals

Chapter 4: Sharing Files and Resources on a Network

Chapter 5: Running Windows on a Mac

Chapter 6: Maintenance and Troubleshooting

Chapter 1. Backing Up and Restoring Your Data

In This Chapter

arrow Considering your options for backing up

arrow Using Time Machine to recover files

arrow Transferring your data to a new Mac with Migration Assistant

arrow Recovering files you’ve lost

Backing up data is something that many people routinely ignore, like changing the oil in the car on a regular basis. The only time most people think about backing up their data is after they’ve already lost something important, such as a business presentation or a folder full of close-to-the-heart family photos. Of course, by that time, it’s already too late.

Backing up your data may not sound as exciting as playing video games or browsing the web, but it should be part of your everyday routine. If you can’t risk losing your data, you must take the time to back it up. The good news is that your Mac came with Time Machine, the application that makes backing up a routine that your Mac can do on its own.

In this chapter, we explain some of the different backup options. Next, we show you how to set up Time Machine to perform regular automatic backups. We also talk about recovering an individual file and restoring your Mac with the Time Machine backup in the unfortunate event that you lose all your files. We include a brief explanation of AutoSave and Versions, which you find in Apple apps such as Pages and Keynote. We explore storing your data online with third-party services. If you purchase a new Mac, you’ll want to make a backup of your old Mac and then move all your stuff to the new one — we tell you how to do that, too.

Understanding Different Backup Options

Backing up is, essentially, duplicating your data — making a copy of every important file. You could duplicate each file as you create it and keep a copy on your hard drive, although this doesn’t solve the problem if your hard drive crashes or your Mac is stolen. Ideally, you back up to one of the following external sources (we explain each of these in the following sections):

· External hard drive — personal or networked, such as Time Capsule

· Flash drive

· Remote storage, such as Dropbox or SugarSync

· CD-R or DVD-R

You must make sure to back up periodically, such as at the end of every week, or even every day if you update and create new files often. If you forget to back up your files, your backup copies could become woefully outdated, which can make them nearly useless.

Depending on the value of your files, you may want to consider using more than one backup method. For example, you may want to use Time Machine to completely back up your Mac on a weekly basis but depend on its hourly and daily backups for changes to the screenplay you’re writing in Pages on iCloud. The idea here is that if catastrophe strikes and you lose your Mac, you can always replace the applications — but you can’t retake family photos or rewrite your unfinished novel. The more backup copies you have of your critical files, the more likely it is that you’ll never lose your data no matter what might happen to your Mac.

Backing up with external hard drives

To prevent the loss of all your data if your hard drive should suddenly bite the dust, you can connect an external hard drive to your Mac’s USB or Thunderbolt port with a cable that’s typically included with the hard drive.

image USB and Thunderbolt ports connect peripherals to a computer. USB ports commonly connect a mouse, printer, or digital camera. Thunderbolt connects a display or storage device. The main advantage of using external hard drives is that copying large files is much faster and more convenient than copying the same files to CDs or DVDs. Additionally, external hard drives are easy to unplug from one Mac and plug into another Mac; plus, only one of the newest Mac models even has an optical disc drive.

You can also put an external hard drive on your network. For example, Apple’s Time Capsule provides external storage and functions as a Wi-Fi hub so multiple computers can back up to the Time Capsule. (There are 2TB and 3TB (terabyte) versions, so you probably won’t have to worry about storage space.) Any networked drive must use Apple File Protocol (AFP) file sharing.

Perhaps the biggest drawback of using external hard drives is that they can’t protect against a catastrophe near your computer, such as a fire burning down your house or a flood soaking your computer desk and office. If a disaster wipes out the entire area around your computer, your external hard drive may be wiped out in the catastrophe as well.

You can treat an external hard drive as just another place to copy your files, but for greater convenience, you should use a special backup application, such as Time Machine, which we get to in shortly, in the section “Blasting into the Past with Time Machine.” Backup applications can be set to run according to a schedule (for example, to back up your files every night at 6 p.m.)

If the files haven’t changed since the last time you backed them up, the backup application saves time by skipping over those files rather than copying the same files to the external hard drive again.

image To retrieve files, you could just copy the files from your external hard drive back to your original hard drive — but be careful! If you changed a file on your original hard drive, copying the backup copy can wipe out the most recent changes and restore an old file to your hard drive, which probably isn’t what you want. To keep you from accidentally wiping out new files with older versions of that same file, backup applications always compare the time and date a file was last modified to make sure that you always have copies of the latest file.

Storing backups on USB flash drives

Because of their low cost, fast copying speed, and ease of moving and plugging into any Mac, flash drives are a popular alternative for backing up files. Many USB flash drives have built-in key rings. Carrying one in your pocket or purse not only is convenient, but also ensures that your data is always safe and on your person should something happen to your Mac’s hard drive at home or in the office, where your backup drive’s original files are stored.

The biggest drawback of USB flash drives is their somewhat limited storage capacities, which typically range from 8GB to 128GB or sometimes more. USB flash drives in those capacity ranges can usually cost between $10 and $100, but a whopping 512GB model sold by Amazon ( costs around $600 as of this writing. Whatever the capacity, USB flash drives are especially convenient for carrying your most critical files but not necessarily for backing up all your important files. In contrast to the hassles of writing (or burning) data to a CD or DVD, saving files to a USB flash drive is speedier and as simple as saving a file to a backup folder on your hard drive.

image We found a 256GB flash drive for $3.50 (!), but it uses USB 2.0, which is the older transfer protocol. So you have a fair amount of storage but the transfer speed is s-l-o-w. Make sure the flash drive you choose uses USB 3.0, like the newest Macs. Of course, if you have an older Mac, you may have to use a USB 2.0 flash drive to match the USB port on your Mac.

Storing backups off-site

Backing up your Mac’s important files to an off-site storage service virtually guarantees that you’ll never lose your data. We explain how they work here but keep in mind that doing a complete remote backup will be slower than a USB 2.0 flash drive and your ISP may limit file transfer sizes. You may want to use an external hard or flash drive for complete backups and then store particularly important documents on remote backup sites.

Low-cost (and even free) off-site storage options are available for Mac users. Many companies sell off-site storage space for a monthly fee. However, to entice you to try their services, they often provide a limited amount of free space that you can use for an unlimited period at no cost. To get your free off-site storage space, sign up with one or more of the following off-site data-backup sites, each of which offers a paid version with more storage space; most have a free option that offers from 2GB to 10GB of storage and then paid options for more storage or multiple users:

· Box ( Free 10GB storage space

· Dropbox ( Free 2GB storage space

· ElephantDrive ( Free 2GB storage space

· iDrive ( Free 5GB storage space

· Mozy ( Free 2GB storage space

· SugarSync ( Free 5GB storage space

· Syncplicity ( Free 2GB storage space

image iCloud is fairly Apple-specific when it comes to online storage. Although iCloud offers 5GB of storage space free, plus up to 1,000 photos and any purchased media, apps, and books, it isn’t a true Mac backup option. iCloud does automatically synchronize the contents of the Contacts, Calendar, Reminders, and Notes apps, as well as Safari bookmarks. iCloud also syncs documents created with an iCloud-enabled app, such as Pages or Numbers, and stored on iCloud between multiple Macs or between your Mac and your iPhone, iPad, iPod touch, or Windows PC. Even if you don’t sync with another device, you can turn on the iCloud services and store your data remotely. However, iCloud doesn’t backup apps not purchased in the App Store or Word documents or that 1,001st photo, so you should consider iCloud as a syncing tool for your Mac and a backup tool only for iOS devices.

Backing up to CDs or DVDs

With the advent of flash drives and remote storage, this section is almost obsolete. In fact, the newest Macs — even iMacs and Mac Pros — don’t come with optical disc drives; you have to use an external drive to write files to CDs or DVDs. But perhaps the biggest drawback of backing up to a CD or DVD is the space limitation: CDs can store up to 700MB of data, single-layer DVDs can store 4.7GB of data, and dual-layer DVDs store up to 8.5GB of data.

image A dual-layer disc employs a second physical layer within the disc, which the drive accesses by shining its laser through the disc’s first, semitransparent layer.

If you need to back up only word-processor or spreadsheet files, a single CD should be sufficient. However, music, video, and digital photographs take up more space, which means that you may need to use several DVDs to back up all your files. The more discs you need to back up your files completely, the harder it is to keep track of all the discs — and the slower (and more tedious) your backups are to make. In view of all this hassle, you may not back up your data as often as you should; eventually, your backup files fall too far out of date to be useful, which defeats the purpose of backing up your data. So, if your data frequently exceeds the storage limits of a single CD or DVD, you should probably rely on a different backup method.

Blasting into the Past with Time Machine

One problem with traditional backup applications is that they store the latest, or the last two or three previous, versions of your files. Normally, this is exactly what you want, but what if you want to see an earlier version of a short story you began working on two weeks ago? Trying to find files created on certain dates in the past is nearly impossible, unless you do one of the following:

· Keep a copy of the backup you made previously.

· Save different versions of the document.

· Work with applications that support Versions. We explain this in the “Understanding Versions” section, later in this chapter.

Fortunately, that type of problem is trivial for your Mac’s backup application, Time Machine. Unlike traditional backup applications that copy and store the latest or last one or two versions of files, Time Machine takes snapshots of your Mac’s storage drive so that you can view its exact condition from two hours ago, two weeks ago, two months ago, or even farther back.

image The external hard drive you use to back up your Mac with Time Machine should have oodles of storage space, and ideally, you use that drive only for Time Machine backups. The bigger the hard drive, the farther back in time you can go to recover old files and information.

By viewing the exact condition of what your Mac storage drive looked like in the past, you can see exactly what your files looked like at that time. After you find a specific file version from the past, you can easily restore it to the present with a click of the mouse.

Setting up Time Machine

To use Time Machine, you need to connect an external hard drive to your Mac with a USB or Thunderbolt cable, or you may have an additional hard drive installed in one of the additional drive bays inside an older Mac Pro desktop computer (the new 2013 Mac Pro models don’t have multiple drive bays).

image If you use an external drive that doesn’t have its own power supply, connect your Mac to a power supply because your Mac supplies the juice to the external drive.

To set up Time Machine to back up the data on your Mac’s primary hard drive to an external hard drive, follow these steps:

1. Connect the external hard drive to your Mac.

image When you plug in a new hard drive, the Time Machine backup feature typically starts automatically and asks whether you want to use the hard drive to back up your Mac. Another choice asks whether you want to encrypt the backup disk, which will scramble the data until you access it. Otherwise anyone who gets his or her hands on your external backup drive can read your data.

If Time Machine automatically runs and prompts you as described, skip to Step 4. If Time Machine does not prompt you, continue to the next step.

2. Choose image⇒System Preferences and then click the Time Machine icon to open the Time Machine preferences pane, as shown in Figure 1-1.


Figure 1-1: To set up Time Machine, turn it on and choose an external drive to use.

3. (Optional) If you want to exclude files from your backup or your backup disk has limited storage, skip to the section “Skipping files you don’t want to back up” and then return to Step 3 here.

4. Click the On button.

A dialog appears, listing all available external hard drives you can use, as shown in Figure 1-2.


Figure 1-2: You must choose an external hard drive to use with Time Machine.

5. Select an external hard drive and, optionally, select the Encrypt Backups check box if you want to encrypt the files saved to your backup drive. (See Book III, Chapter 2 to discover more about encryption.)

6. Click the Use Disk button.

If you chose to encrypt your disk, the password creation screen opens. Do the following:

1. Click the key button if you want help creating a password or go directly to the next step.

Password Assistant (shown in Figure 1-3) opens and rates the security (quality) of your password. Manual lets you create your own password, or choose a type from the pop-up menu to see and select suggested passwords; drag the slider to define the password length. When you see a password you like, simply close the Password Assistant window and the selected password is assigned.


Figure 1-3: Use Password Assistant to create a memorable, secure password.

2. Type a password in the first field and then type it again in the second field to verify it.

image If you forget your password, you can’t restore your Mac from your backup drive, so choose wisely.

3. Type a password hint in the third field.

4. Click Encrypt Disk.

Time Machine prepares your backup disk for encryption.

After preparing the drive, the Time Machine pane appears again, listing your chosen external hard drive, and after a short amount of time, the Time Machine application begins backing up your Mac’s data to the external hard drive you selected.

7. (Optional) Select the Show Time Machine in Menu Bar check box if it isn’t already checked.

With this option checked, the Time Machine icon on the menu bar animates with a twirling arrow whenever Time Machine is backing up your Mac’s data. Clicking the Time Machine icon at any time (see Figure 1-4) is how you can keep tabs on the status of an active backup, start or stop a backup, and choose the Enter Time Machine command to run the Time Machine recovery application, as described in the upcoming section, “Retrieving files and folders.”


Figure 1-4: Access your Mac’s backup options from the menu bar.

8. Click the Close button to close the Time Machine preferences pane.

image Don’t interrupt Time Machine during the first backup. You can continue working while Time Machine runs in the background.

Skipping files you don’t want to back up

Unless you specify otherwise, Time Machine backs up everything on your Mac to which your account has access except temporary files, such as your web browser’s cache. To save space, you can identify certain files and folders you’re not concerned about losing that you want Time Machine to ignore. For example, you may not want to back up your Applications folder if you already have all your applications stored on separate installation discs or you purchased them through the App Store, which lets you download them again if necessary. Or you may choose to skip backing up media you purchased and downloaded from iTunes because if you lose them you can download them again, so there’s no need to waste that precious space on your Mac’s backup drive.

To tell Time Machine which files or folders to skip, follow these steps:

1. Choose image⇒System Preferences and then click the Time Machine icon to open the Time Machine preferences pane (refer to Figure 1-1).

2. Click the Options button to open the Exclude These Items from Backups dialog.

3. Click the plus sign (+) and then navigate through the mini-Finder window to the file or folder you want Time Machine to ignore.

image You can select multiple drives, files, and folders by holding down the image key and then clicking what you want Time Machine to ignore.

4. Click the Exclude button.

The Exclude These Items from Backups dialog appears again, as shown in Figure 1-5. Your backup disk appears first in the list. Next to each excluded item, you see the amount of storage it would occupy if you backed it up; below the list, you see the estimated size of your backup.


Figure 1-5: Click the plus sign (+) to choose files you don’t want to back up.

5. Select or deselect these additional optional Time Machine features if you want:

· Back Up While on Battery Power: This option allows Time Machine to back up your MacBook when it’s running on battery power. Turning on this option will drain your MacBook’s battery faster.

· Notify After Old Backups Are Deleted: Time Machine displays a dialog requesting your approval before it deletes any old backup files.

6. Click the Save button.

7. Click the Time Machine On button, if it’s not clicked already.

Return to Step 4 of the previous instructions to continue.

How Time Machine does its backup thing

The first time you turn on and begin using Time Machine, it backs up the specified data from your user account on your Mac’s hard drive (if you’re the only user, it backs up everything), which can take a long time if your Mac’s hard drive contains lots of applications and data. One thing you can do is start the Time Machine backup before going to bed so when you wake the next morning, your Mac will be completely (or almost completely) backed up — make sure PowerNap is on in image⇒System Preferences⇒Energy Saver so Time Machine works even if your Mac falls asleep.

After its initial backup of your Mac’s hard drive, Time Machine automatically performs an incremental backup of any data changed on your Mac’s hard drive (providing the backup drive is attached) every hour. Time Machine saves hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for everything older than a month. Time Machine skips backing up files you create and then delete before the next hourly backup.

When your external backup hard drive starts running out of free space for more backups, Time Machine deletes the oldest files it finds in order to make room for the newer ones.

If you use a portable Mac, when the external drive isn’t connected, Time Machine saves a snapshot on your Mac’s internal drive; the next time you connect the external drive, the backup resumes.

image You may want to control the time and frequency of Time Machine backups — a feature that Time Machine itself doesn’t offer. Although you could just connect your external backup drive only when you want to perform a backup or go into the Plist (pronounced pea-list) of your Mac (a place where technical information is kept) and rewrite the instructions, you may be better purchasing an app called Time Machine Backup Scheduler from the App Store ($3.99, Voros Innovation,, which does the instructing for you.

Retrieving files and folders

Time Machine consists of two components:

· The Time Machine preferences pane (described earlier in this chapter; refer to Figure 1-1): Turn the Time Machine backup feature on or off, or adjust its settings.

· The Time Machine restore application: Recover files you deleted or changed from earlier backups. You run the restore application by clicking the Time Machine icon on the Dock or on the Launchpad, or by choosing the Enter Time Machine command from the Time Machine icon on the menu bar (refer to Figure 1-4).

After you configure Time Machine to back up your Mac, you can use the Time Machine recovery application to retrieve old files or information you deleted or changed after Time Machine backed them up. The two ways to use the Time Machine recovery application to recover files, folders, or other pieces of information, such as address cards, e-mail messages, or events from Calendar, are as follows:

· By running an application and then clicking the Time Machine icon on the Dock or Launchpad, or choosing the Enter Time Machine command from the Time Machine icon on the menu bar

· By opening a new Finder window and then clicking the Time Machine icon on the Dock or on the Launchpad, or choosing the Enter Time Machine command from the Time Machine icon on the menu bar

Recovering data from within an application

To use Time Machine to retrieve a specific piece of information from within an app (such as an address card from your Mac’s Contacts app, which we use in this example), follow these steps:

1. Click the Contacts icon on the Dock or on the Launchpad to launch Contacts.

The Contacts app opens and displays the Contacts window, which lists all your contacts.

2. Click the Time Machine icon on the Dock or Launchpad (or click the Time Machine icon on the menu bar and choose Enter Time Machine) to run the Time Machine restore app.

Your Mac’s screen will appear to space out while it launches the Time Machine restore app — into another dimension known as The Time Machine Zone, as shown in Figure 1-6.


Figure 1-6: The Time Machine restore application displays a far-out view of Contacts.

3. Choose one of the following ways to select a contact card (or cards) that you want to restore from a past backup:

· Click the Backward and Forward arrow buttons near the bottom-right corner of the screen. Click the Backward button to move the Contacts window backward in time to earlier Time Machine backups. Click the Forward button to move forward to more recent Time Machine backups.

· Click a Contacts window in the stack of windows behind the frontmost Contacts window. You can click the Contacts window directly behind the front Contacts window, or one behind it stretching farther back in time. Each time you click a Contacts window in the stack, Time Machine moves it to the front of the screen.

· Move the pointer to the Time Machine timeline along the right edge of the screen. The timeline bars expand to display a specific date. To choose a specific date, click it.

4. When you locate the contact card you want to retrieve, click it, click the Restore button in the lower-right corner, and then proceed to Step 6.

image To select more than one contact card, hold down the image key and click each additional contact you want to recover.

5. If the contact you want to restore is nowhere to be found in the Contacts windows — or if you change your mind and don’t want to recover a backed-up contact — click the Cancel button in the lower-left corner (or press the Escape key).

Time Machine closes and returns you to the present.

6. The Time Machine Contacts window zooms forward and then closes, returning you to the Contacts application window, which now includes the recovered contact card (or cards).

That’s it — you’ve been saved!

image You can search within Time Machine to locate the file you want to retrieve from a previous backup by typing in a search term in the search field. You can also use Spotlight Search from the Finder, and then click the Time Machine icon on the Dock or Launchpad. When you find the file you want, select it and click the Restore button. The item is placed in its original location.

Retrieving files and/or folders by using the Finder

To use the Finder window to retrieve files, folders, or a combination of both with the Time Machine restore app, follow these steps:

1. Click the Time Machine icon on the Dock or on the Launchpad (or click the Time Machine icon on the menu bar and choose Enter Time Machine) to run the Time Machine restore app.

2. Choose one of the following ways to locate the file or folder from the past that you want to recover by using the Finder window:

· Click the Backward and Forward arrow buttons near the bottom-right corner of the screen. Click the Backward button to move the Finder window backward in time to previous Time Machine backups. Click the Forward button to work your way forward to more recent Time Machine backups.

· Click a Finder window behind the frontmost Finder window. Each time you click a Finder window, Time Machine moves it forward to the front of the screen.

· Move the pointer to the Time Machine timeline along the right edge of the screen. The timeline bars expand to display a specific date. To choose a specific date, click it.

image To take a peek at the contents of a particular document, picture, audio track, or other file, click it and then click the Quick Look button on the toolbar (see Figure 1-7), which gives you a speedy way to view the contents of your selected file to make sure that it’s the one you really want to recover. The file type needs to be one that Quick Look understands. Quick Look can’t read some database applications, such as FileMaker and Bento, nor most CAD documents.

3. When you locate the data you want to recover, select the file or folders, click the Restore button in the bottom-right corner of the screen, and then proceed to Step 5.

image To select more than one file or folder, hold down the image key and click each additional item you want to recover.


Figure 1-7: Take a peek with Quick Look view.

4. If the data you want to recover is nowhere to be found in the Finder windows — or if you change your mind and don’t want to recover backup data — click the Cancel button in the bottom-left corner (or press the Escape key).

The Time Machine recovery application closes, and you return to the present.

5. The Time Machine Finder window zooms forward and then closes, safely returning you to a Finder window that now includes your recovered file or folder.

Consider yourself saved!

Understanding Versions

Some apps — such as Apple’s iWork apps, TextEdit, and Preview — have AutoSave and Versions functions, which automatically save your files while you work. AutoSave saves your document whenever you make changes. If you make a series of changes that you don’t want to lose, you can choose to lock the document at that point. You have to unlock it to make future changes or use it as a template for a new document. To lock a document, hover the pointer near the file name at the top center of the window, click the disclosure triangle that appears and then click the check box next to Locked.

Versions takes a snapshot of your document when it’s new, each time you open it, and once hourly while you’re working on it. Versions keeps those hourly snapshots for a day, saves the day’s last version for a month, and then saves weekly versions for previous months. If at some point you want to go back to an earlier version, choose File⇒Revert To⇒Browse All Versions, and Time Machine shows snapshots of that document, as shown in Figure 1-8. You can make side-by-side comparisons and cut and paste between them.


Figure 1-8: Versions is like having a mini Time Machine inside an app.

Restoring your entire backup

If your system or startup disk is damaged, you may have to restore your entire backup to your Mac. If you use Time Machine, you’re worry free. Here’s how to restore your Mac with Time Machine:

1. Connect the backup drive to your computer.

If you use a networked drive, make sure that your computer and the drive are on the same network.

2. Choose image⇒Restart and hold down image+R while your Mac restarts.

If you can’t access the image menu — that is, your Mac is off and won’t boot — hold down image+R and press the On button. See Book III, Chapter 6 for more information about troubleshooting.

3. Choose the language you use when the language chooser appears, and then click the arrow button (Continue).

4. Select Restore from a Time Machine Backup and then click Continue.

5. Choose the drive where your backup is stored:

· Select the external drive and click Continue.

· Select Time Capsule or the networked drive and click Connect to Remote Disk.

6. Enter the username and password if requested.

7. Select the date and time of the backup you want to use.

Time Machine begins copying your backup from the drive to your Mac.

8. Breathe a sigh of relief that you back up regularly!

Moving Your Backup from an Old Mac to a New Mac

Sooner or later, your Mac will be outdated, and you’ll want to move your files to a new Mac. Apple has a handy Migration Assistant application to perform this task. You can transfer your files directly by connecting one Mac to the other with a Thunderbolt cable or over a network. If the old Mac is kaput, however, you can use your Time Machine backup. Follow these steps:

1. On the new Mac, click the Launchpad icon on the Dock, open the Utilities folder, and then click Migration Assistant.

The Migration Assistant Introduction dialog opens, as shown in Figure 1-9.


Figure 1-9: Migration Assistant transfers your existing files to your new Mac.

2. Click Continue.

Migration Assistant automatically quits any open apps, the Desktop closes, and a Migration Assistant window opens.

3. Select the From Another Mac, Time Machine Backup, or Startup Disk option and then click Continue.

Enter the password for your computer, if asked. The Select a Migration Method dialog opens.

4. Choose the From a Time Machine Backup or Other Disk option button and click Continue.

Migration Assistant searches for external drives.

5. Select the drive from which you want to transfer your backup.

6. Select the information you want to transfer.

· Users includes all the user’s media, documents, messages, contacts, and calendars.

· Applications transfers applications that are compatible with the new Mac.

· Settings transfers personal settings. Check Computer to transfer your desktop image and other personal settings; check Network (not shown in the figure) to transfer your network settings.

7. Click Continue.

Migration Assistant begins transferring the selected files.

image If your new Mac has a newer operating system than your old Mac, applications that aren’t compatible with the new operating system may not work or even be transferred. Choose image⇒Software Update to find and install any application updates that are compatible with the operating system of your new Mac.

Working with Data-Recovery Programs

Data-recovery apps work by taking advantage of the way computers store and organize files by physically placing them in certain areas, known as sectors, on your Mac’s internal storage drive (or removable storage device). To find out more about the nitty-gritty of how hard drives manage files, check out the nearby sidebar, “Hard drive: A tale of control, corruption, and redemption.”

Suppose you’re a well-protected Mac user who backs up your data regularly. You’re completely safe, right, and you never have to worry about losing files you can’t retrieve? Not exactly. Here are three situations where backup applications can’t help you, and you may need to rely on special data-recovery applications instead:

· Accidental deletion from the hard drive: The most common way to lose a file is by accidentally deleting it. If you try to recover your lost file through a backup app, such as Time Machine, you may be shocked to find that your backup app can recover only a version of your file from the previous hour or older, but not from the span of time between Time Machine backups. So, if you spent the last 45 minutes changing a file and accidentally deleted it before Time Machine could run its next automatic backup, you’re out of luck if you want to recover the changes you made in the last 45 minutes.

image Even if you format and erase your entire hard drive, your files may still physically remain on the hard drive, making it possible to recover those files.

· Hardware failure: Another way to lose a file is through a hardware failure, such as your hard drive mangling portions of its disk surface. If a power outage knocked out your Mac without properly shutting it down first, any open files that you were working on or that were stored may be corrupted. Such a failure can go unnoticed because the hard drive still works. As a result, your backup app copies and saves these mangled versions of your file. The moment you discover your file is corrupted, you also find that your backup app has been diligently copying and saving the same corrupted version of your file.

· Deletion from removable media: You may lose data by deleting it from removable media, such as a USB flash drive or digital camera flash memory card (such as a Compact Flash [CF] or Secure Digital [SD] card). Most likely, your backup apps protect only your hard drive files, not any removable storage devices, which means that you could take 20 priceless pictures of your dog doing midair back-flip Frisbee catches, only to delete all those pictures by mistake (and tanking your dog’s chances at YouTube stardom). Because your backup app may never have saved those files, you can’t recover what was never saved.

image Hard drive: A tale of control, corruption, and redemption

To keep track of where each file is stored, your Mac maintains a directory that tells the computer the names of every file and the exact physical location where each file begins. Files are divided into blocks, and (typically) the end of each block contains a pointer to the next block of that file. This division is transparent to you, the user; when you open a file, you see all the blocks together. When different apps, such as word processors or spreadsheets, need to find and open a file, these apps depend on the Mac operating system to keep track of this directory so they know where to find a file.

When you delete a file, the computer simply removes that file’s name from the directory. The blocks that make up your file still physically exist on the disk surface, but the computer can’t find and assemble them again. Therefore data-recovery apps ignore the disk’s directory listing and search for a file by examining every part of the entire storage device to find your missing files, locating the beginning of the first block and then following the pointers at the end of each block that indicate the beginning of the next one, creating a chain of blocks that make up the whole file.

If you didn’t add any files since you last deleted the file you want to retrieve, a data-recovery app will likely retrieve your entire file again. If you saved and modified files since you last deleted a particular file, there’s a good chance any new or modified files might have written over the area that contains your deleted file. In this case, your chances of recovering the entire file intact drops rapidly over time.

If a hardware failure corrupts a file, all or part of your file might be wiped out for good. However, in many cases, a hardware failure won’t physically destroy all or part of a file. Instead, a hardware failure might physically scramble a file, much like throwing a pile of clothes all over the room. In this case, the file still physically exists, but the directory of the disk won’t know where all the parts of the file have been scattered. So, to the computer, your files have effectively disappeared.

A data-recovery application can piece together scattered files by examining the physical surface of a disk, gathering up file fragments, and putting them back together again like Humpty Dumpty. Depending on how badly corrupted a file might be, collecting file fragments and putting them back together can recover an entire file or just part of a file, but sometimes recovering part of a file can be better than losing the whole file.

Some popular data-recovery applications include

· Data Recovery for Mac (; $90): Specializes in recovering files from corrupted or reformatted hard drives.

· Data Rescue 3 (; $99): Recovers and retrieves data from a hard drive your Mac can no longer access because of a hard disk failure.

· DiskWarrior 4 (; $100): Builds a new replacement directory, using data recovered from the original directory, thereby recovering files, folders, and documents that you thought were gone forever.

· Klix (; $20): Recovers lost digital images stored on flash memory cards, such as SD or CF cards.

· Softtote Data Recovery Mac (; $70): Retrieves lost, formatted, deleted, corrupted, and infected files.

The art of computer forensics

Most anything you store on your Mac can be recovered, given enough time and money. When most people lose data, they’re thankful when a data-recovery app can retrieve their files. However, in the criminal world, people may want to delete files so that nobody can ever find them again, to hide evidence. To retrieve such deleted files, law enforcement agencies rely on computer forensics.

The basic idea behind computer forensics is to make an exact copy of a hard drive and then try to piece together the deleted files on that copy of the original hard drive. Some criminals have lit hard drives on fire, poured acid on them, and sliced them apart with a buzz saw — and law enforcement agencies still managed to read and recover portions of the files from the slivers of hard-drive fragments that contained magnetic traces of the original files.

The good news is that if you can’t recover a file yourself by using a data-recovery application, you can often hire a professional service that can recover your data for you — but that data better be really important to you because data-recovery services are very expensive.