Is your external backup hard drive full of Time Machine backup data? In last week’s Tech Tip, we talked about how Time Machine automatically deletes your oldest backups to make room for new backups. Time Machine typically does this, but I’ve seen it misbehave also. Alternatively, you might want to manually delete some of your old Time Machine backups to free up space on the external hard drive for some other use. In any case, here are instructions on how to manually delete some Time Machine backups.

On your Mac’s Desktop, double-click the icon of the external hard drive that stores your Time Machine backup data.

You’ll see a folder with the curious name of Backups.backupdb. Open this folder.

Inside you’ll see  a separate folder for each Macintosh computer that is backed up to this drive. If you only backup one Mac, then you’ll only see one folder. The folder is typically named something like Susan’s iMac. Open the folder containing the backups you want to delete.

Wait for the contents to be displayed. It could take a minute. Eventually, you’ll see a list of folders whose names are comprised of date and time stamps. Each of these folders contains backup data created by Time Machine.

Select one of more of these folders, typically the oldest ones, and drag them to the Trash icon on your Dock.

Empty the Trash by going to the Finder menu and selecting Empty Trash.

Sit back and wait while the Trash is emptied. You’ll be surprised how long this process takes. An even bigger surprise is that the status messages will indicate that the number of items to be deleted is a negative number. Of course this is illogical, but it will be displayed. Don’t worry about it. The deletion will eventually finish.

Has your Time Machine backup hard drive filled up? Are you seeing the “Time Machine deleted one or more backups to make room for new backups” notification? If so, don’t worry. This is perfectly normally and is probably just fine. Let me elaborate and explain.

Let’s briefly review how Time Machine works. Let’s imagine you setup Time Machine on July 17, 2010. The first time it performs a backup it copies all files onto the external backup hard drive. This means that it copies the Mac operating system, as well as all applications and all of your photos, music, Word files, etc. Time Machine continues to automatically perform backups every hour when the Mac is on, awake and the backup hard drive is connected. These subsequent backups are much, much smaller than the initial backup. These subsequent backups only include new and edited files and are called incremental backups. Time Machine regularly prunes, or deletes, some of these small incremental backups. In other words, it doesn’t hold onto each and every hourly backup. Instead, it holds onto hourly backups for the past 24 hours, daily backups for the past month, and then weekly backups until the hard drive is full.

Once the hard drive is full, it displays a message indicating that it’s going to delete your oldest backup, from July 17, 2010 in my example. However, Time Machine is smart enough to always hold onto at least one copy of every file on your Mac. In other words, if you created a Word file named My Resume on Jan 1, 2007 and haven’t edited or opened that file since then, Time Machine backed up this file when it was initially setup. So, even though Time Machine is now deleting some backups from July 2010, it still has one copy of that Word file you created on Jan 1, 2007. Thus all of the files on your Mac are still protected (backed up). All that is being deleted are backups of files that you deleted as well as previous versions of documents that you still have. Since you only have one version of My Resume, that sole copy is retained.

If you no longer want to be notified when Time Machine deletes your oldest backups, you can turn off this feature. Go to the Apple menu, select System Preferences and then click on Time Machine. Click the Options button and uncheck the box labeled “Notify when old backups are deleted.”

If the external hard drive on which you store your Time Machine backups can only hold a few weeks worth of incremental backups before you’re notified that your oldest backups are being deleted, then I recommend that you buy an external hard drive with a larger storage capacity. If you choose to do this and want to move your existing backups to your new backup hard drive, you can copy the backups.backupdb folder as described on Apple’s web site.

Next week’s Tech Tip will cover how to manually delete your Time Machine backups from an external hard drive if Time Machine fails to do so on its own.

This Tech Tip covers provides you with instructions on how to setup and monitor Time Machine. It also explains some basic concepts behind Time Machine’s operation. Monitoring your backup system is incredibly important to do. A backup system that isn’t working is useless. Don’t simply trust or believe that your backup system is working. Check on it regularly.

Time Machine is Apple’s backup application which comes bundled with Mac OS X. It was introduced in 2007 as part of Mac OS X 10.5, Leopard. I have other Tech Tips that talk about encrypting Time Machine backups, swapping between two hard drives when using Time Machine and restoring a file from Time Machine.

Setup – Time Machine is the easiest backup application to setup. For many users it can be as easy as connecting a brand new external USB or Firewire hard drive to your Mac and turn it on. When you turn it on it’ll mount (appear) on the Desktop. Time Machine will detect this hard drive and present an on-screen message asking if you’d like to use this hard drive for storing Time Machine backups, click the “Use as backup disk” button and you’re done.

While it can be this easy, there can be complicating factors, including these:

If Time Machine has previously been configured to use some other hard drive then you’ll need to manually configure it to use this new hard drive. To accomplish this, go to the Apple menu, select System Preferences and click on Time Machine, then click the “Select Disk” button. Select the new hard drive from the list.

If the new hard drive is formatted as a PC hard drive using FAT32 or NTFS formats then Time Machine will prompt you to re-format the hard drive. I tend to buy my hard drives from Other World Computing or some other Mac-oriented vendor since their hard drives always come pre-formatted as a Mac hard drive using Mac OS Extended (Journaled). I also tend to buy hard drives with FireWire ports as opposed to only USB ports since there are often a lot of USB devices vying for the relatively few USB ports on a Mac.

Initial Backup – Once Time Machine is configured to use a particular hard drive, backups will automatically occur every hour as long as the Mac is on and awake and the selected hard drive is available. The first backup will start within two minutes of you selecting it. The first backup can take many hours but you can continue to use the computer while the backup is running. I typically start the initial Time Machine backup near the end of the day. This way it can run all night as needed.

Which files are backed up? Time Machine backs up nearly all files on your Mac. It backups all of your data files (music, email, bookmarks, photos, etc) as well as applications (Word, Safari, iTunes, etc) and Mac OS X itself. It’s useful to know that it does not backup files in the Trash. It also does not backup most cache files, log files and the iPod photo cache. You also have the ability to manually exclude a file or folder by going back to System Preferences and clicking on Time Machine, then clicking the “Options” button and adding an item to the list.

Backup Retention – After the initial backup is complete, subsequent backups only add new and/or modified files. Subsequent backups run automatically every hour, however not every backup is kept for ever. If every hourly backup was kept forever your backup hard drive would fill up very quickly. Instead, Time Machine automatically does some pruning of old backup files. Hourly backups are kept for the past 24 hours. Beyond 24 hours, daily backups are kept for one month. Beyond that, weekly backups are kept until the backup hard drive is full. Once the backup hard drive becomes full, Time Machine will notify you that it needs to delete the oldest backups in order to make room for the newest backups. I typically recommend using a backup hard drive which has at least twice the amount of storage space as you have files. For example, my laptop has about 150 GB of stuff on it. Thus, I should use a backup drive that is at least 300 GB in storage capacity.

Day-to-Day Monitoring – After you’ve setup Time Machine, the next most important task you can do is monitor Time Machine to ensure that it’s operating properly. A backup system that isn’t working is useless. To monitor Time Machine simply click on the Time Machine icon located in the upper right corner of your screen near the clock. The Time Machine icon looks like an arrow curving around in a circle with clock hands inside the circle. Click on this icon and read the first line. It should read  ”Latest Backup: Today 2:15 pm” or something similar. If your most recent backup wasn’t today then you should select “Back Up Now” from the Time Machine menu. The Time Machine menu icon should begin to spin backwards. You can then click on it to monitor the status of the backup. Commonly seen messages are Preparing, Backing up X Megabytes of XYZ Megabytes, and Cleaning Up.

If your Time Machine backup system is not working properly, the most common cause is that your backup hard drive has become disconnected or is turned off. Do you see your backup drive’s icon on the Desktop? If not, check for loose cables and to make sure that it’s turned on. Also, disconnect and then reconnect the cable which connects the hard drive to your Mac.  If you’re still not able to get the backup drive to show up then restart your Mac. Afterwards, manually start Time Machine to see if it works now. If it’s still not working, you could refer to either of the web sites I list below or contact your Mac support person for assistance.

Restore – It’s best to know how to restore a file from your Time Machine backup before a crisis hits. Thus, you should practice performing a restore in order to get comfortable with the procedure. This way you can remain calm should a crisis arise. I’ve written a separate Tech Tip about how to restore files from Time Machine.

Apple’s introduction to setting up, restoring from and troubleshooting Time Machine.

Mr. Pondini has created a very thorough web site about Time Machine, including extensive Frequently Asked Questions and Troubleshooting sections.

Is your Time Capsule full? Would you like to free up some room for either newer backups of your data or to add another computer in your home? If so, here are some instructions on  this process.

[Note: You need to be comfortable using Terminal and issuing some basic Unix commands in order to free up storage space. You can really mess things up if you use Terminal and are not sure what you're doing, so hire a consultant if you're unsure.]

Time Machine uses different methods for storing data on local (USB or Firewire) hard drives versus the hard drive in a Time Capsule. On a Time Capsule hard drive, Time Machine stores your backup files in a special type of disk image known as a sparsebundle. You don’t need to know what a sparsebundle is, but it’s important to understand that it has important implications when it comes to freeing up space on a Time Capsule hard drive.

On a local hard drive, if you want to delete some of the backup data, you open Time Machine and select the date of a particular backup. Then, click on the Action menu icon, which looks like a gear in the Finder window, and select Delete Backup. Time Machine will proceed to delete the files in that particular backup and this will free up space on the local hard drive.

On a Time Capsule hard drive, when you follow this same procedure to delete the files in a particular backup, you don’t free up storage space on the Time Capsule since the sparsebundle disk image does not change in size. To reclaim the storage space you need to issue a command to shrink the sparsebundle disk image. Here are the steps:

• Open the Terminal application and type cd /Volumes/
• Select your Time Capsule hard drive and navigate into its subdirectories to find the correct .sparsebundle file. The sparsebundle file will have the general form of ComputerName MACaddress.sparsebundle. Write down the name of this file, as you’ll need it in a second.
• Type the following command in Terminal: hdiutil compact SparsebundleName.sparsebundle
• Now sit back and wait. Depending upon how many backups you deleted and how large your sparsebundle was when you started, this compacting could take anywhere from a few minutes to overnight.

When the compacting is complete you’ll see that you have more storage space available on your Time Capsule.

Would you like to secure your Time Machine backup data so other people wouldn’t be able to view your files in case your backup drive fell into the wrong hands? Apple doesn’t provide a built-in way to encrypt your Time Machine backup files, but it can be done. A clever individual named Jay has figured out how to do it and has the best documentation that I could find on how to setup encrypted Time Machine backups. Thanks Jay. [Update, Fall 2011: Mac OS X Lion's version of Time Machine now includes a built-in way to encrypt a backup hard drive and its contents. Turning on encryption is now as easy as checking a box in Time Machine Preferences. If your backup drive is empty then the drive can be encrypted in about a minute. If the backup drive already has data on it then it can take many hours to encrypt the entire drive.]

In previous Tech Tips, I’ve written about how useful Time Machine can be as well as how to setup Time Machine and test your Time Machine backups. Apple got a lot of things right when they created Time Machine. It’s by far the easiest backup system to setup, monitor and use to restore a file. Having said that, it does have some short-comings including the fact that it doesn’t let you automatically switch between multiple hard drives and doesn’t let you encrypt your backup data. I describe how to manually switch between drives but Jay offers a way to automate the process. I haven’t tested his method myself but I have successfully setup encrypted Time Machine backups.

Jay provides excellent step-by-step setup instructions but here’s a quick overview.

You obviously need an external hard drive on which Time Machine will store the encrypted data. (Time Machine comes with Mac OS X 10.5 or newer.) Next, you use Disk Utility to create an appropriately named encrypted sparse bundle disk image which you put on the external hard drive. Save the password for your disk image and then move this saved password from your own Login keychain to the System keychain. The disk image then needs to be tweaked slightly so Time Machine will be able to figure out that it can store your data in it. This is accomplished by creating a custom preference (plist) file and putting this plist file into your Disk Image. Finally, select the external hard drive in Time Machine Preferences and Time Machine will magically store the backup data inside the disk image.

Testing your backup system is a critical, but often over-looked task. You need to monitor and test your backup system not only so you know that it’s properly copying your files, but more importantly so you learn how to use your backup system to retrieve a file. By practicing, you’ll be confident and ready when disaster strikes and you need to restore a file.

Time Machine is the easiest, most user-friendly backup program for restoring a file. Here are simple instructions, tested on Mac OS X 10.5 and 10.6, for restoring a file from Time Machine. We’ll imagine that you accidentally deleted a file named My Resume.doc from your Documents folder.

• Click on the Finder icon on your Dock. This will open a Finder window.
• Navigate to your Documents folder.
• Open Time Machine. You can either click on the Time Machine icon in your menu bar and select “Enter Time Machine” or go to your Applications folder and double-click on Time Machine.
• Time Machine’s interface is a star field with a stack of windows disappearing into infinity. On the right-hand edge of the screen, you’ll see a time line. Each of the hash marks corresponds to a different backup copy.
• On the right-hand time line, click on the date and time from which you want to restore your My Resume.doc file.
• You’ll see the top windows in the stack whisk by as Time Machine goes back to the date you selected. Notice that the date and time listed below the Documents window corresponds to the date and time you selected. You’re now looking at your Documents folder the way it looked at that point in the past!
• These windows behave like regular Finder windows. You can navigate around in them or use the search field. You can preview a file by double-clicking it. Click on your My Resume.doc file in your Documents folder to select it. (You can even select an entire folder or hold down the Command key and select multiple files or folders as well.)
• Click the Restore button in the lower right corner. If the name of the file you are restoring matches the name of a file currently stored in the same location, your Documents folder in this case, then Time Machine will ask you if you want to keep either the original item, the restored item or both.
• Your My Resume.doc file will be restored to your Documents folder.

Apple has written similar instructions on how to restore an individual file as well as how to restore your entire hard drive. They also provide an overview of Time Machine.

Update Oct 2010 – Backing up to multiple hard drives is easier to setup if your Mac has Mac OS Mountain Lion (OS X 10.8.x) installed.  One no longer has to go through the rigamarole that I describe below when you swap between two or more hard drives. Instead, Time Machine will remember that you want it to be ready to backup to two or more hard drives. When you swap the hard drives it will automatically start to backup to the hard drive that you just attached. It’s easy to configure Time Machine to backup to multiple drives. Read this article from MacObserver for instructions.

Here are instructions on how to have Time Machine switch between two backup hard drives.

My recommendations for setting up a comprehensive backup system for your Mac include swapping between two external hard drives. While one hard drive is being used to backup your Mac the other drive is kept off-site in a secure location. Using multiple drives provides protection against fire, floods and burglars, which could affect both your Mac and the backup drive sitting next to it.

In last week’s Tech Tip article, I described how to configure Carbon Copy Cloner to perform a full bootable backup whenever the backup drive is reconnected. If you swap your two backup drives on a weekly basis then Carbon Copy Cloner will automatically update it’s full backup each week. In other words, Carbon Copy Cloner can be configured to backup to multiple drives. On the other hand, Time Machine can not be configured to backup to multiple drives. Instead, each time you switch your hard drives you’ll need to manually select the currently attached drive and configure Time Machine to use it.  The good news is that Time Machine will look at the attached hard drive and see that it has stored backup data on this drive previously and will pick up where it left off. It’s important to understand how Time Machine performs its backups.

Time Machine performs automatic incremental updates. Time Machine is scheduled to run automatically every hour as long your Mac is turned on and awake. The first time it performs a backup it can take many hours since it is backing up all files on your Mac. It actually skips some files including items in the Trash, cache files, log files and a few other files. Subsequent backups take much less time since Time Machine only needs to backup modified and new files. It’s also useful to know that Time Machine doesn’t hold onto every hourly backup forever. It performs some automatic deleting of backups. It saves hourly backups for the last 24 hours. Beyond that it saves daily backups for the past month and weekly backups until your hard drive is full. Once a backup drive becomes full then it deletes the oldest weekly backups to make room for new backups and notifies you when it does this.

When you swap backup drives, Time Machine performs a scan to determine what files are new or have been modified since the last time Time Machine performed a backup to a particular drive. In our case, when you swap the drives, the most recent backup would be about a week ago. Time Machine thus performs an incremental backup of all files that are new or have been modified during the past week.

Specifically, here are instructions on how to re-configure Time Machine each time you swap your backup drives. Let’s assume you have two backup hard drives named “Time Machine Red” and “Time Machine Green”. For simplicity, I’ll just call them Red and Green.

1. Let’s assume that Green is currently connected to your Mac. In this case, you’ll see an icon named “Time Machine Green” on your Desktop.
2. Drag this icon to the Trash this tells the Mac to unmount (logically disconnect) the hard drive.
3. It’s now safe to physically disconnect the hard drive from your Mac. Unplug the FireWire or USB cable and power cord, if present, from Green.
4. Connect the power cord, as needed, and FireWire or USB cable to Red.
5. In about 15 seconds you’ll see an icon appear on the Desktop named Time Machine Red. (If your drive is partitioned for use with Carbon Copy Cloner then you’ll see two icons, one for each partition.)
6. Go to the Apple Menu, select System Preferences and click on the Time Machine icon.
7. Click Select Disk
8. Select Time Machine Red from the list of available hard drives.
9. Click the “Use for Backup” button
10. Close the Time Machine Preferences window. Time Machine will start to perform its backup shortly.

Whenever  you swap between Red and Green simply follow these same instructions but replace every occurrence of Red with Green and vice versa. Once you’ve done the swaps a couple of times you’ll see that there’s nothing to it.

In a previous Tech Tip article I encouraged users to setup a comprehensive backup system by partitioning a hard drive into two pieces and then configure Carbon Copy Cloner and Time Machine to  backup to the two partitions. Here are some more detailed setup instructions.

Connect a FireWire or USB hard drive to your Mac with a cable, turn it on and wait for its icon to mount on the Desktop. Go to /Application/Utilities and open Disk Utility. Select the hard drive from the left-hand list. The hard drive is typically named by its size, manufacturer and sometimes a model number. (In the image below you can see that I’ve select the drive named 750.16 GB OEM.)

Paritioning in Disk Utility

Next, click the Partition tab. In the Volume Scheme section select 2 Partitions. Fill in appropriate names and sizes in the fields on the right-hand side. I recommend making the first (top) partition your partition for storing Time Machine backup data and the second (bottom) partition your partition for storing your Carbon Copy Cloner full bootable backup. The reason for putting the Time Machine partition on top is so that you can more easily make the second partition larger, as needed, in the future.

To determine appropriate sizes you should click on your Mac’s hard drive icon on your Desktop. Then go the File menu and select Get Info. Look at how much space, measured in gigabytes (GB) is being used and look at the drive’s total capacity. At a minimum the size for your Carbon Copy Cloner partition needs to be large equal to the number of gigabytes currently used. I typically make the partition at least 10-20% bigger to allow for growth in the amount of data on your hard drive.

I suggest naming the partitions something like Time Machine Backup and Full Backup. If you’re going to follow my recommendation and switch between two backup hard drives then you should add letter or number designators in the partition names, such as Time Machine Backup A.

Set the Format to Mac OS Extended (Journaled).

Click the Options button and make sure you select GUID Partition Table if the drive is connected to a Mac with an Intel processor. Select Apple Partition Map if the drive is connected to a older Mac using a PowerPC G4 or G5 processor. Click the Apply button so the drive will be partitioned and then formatted. When Disk Utility finishes the drive is now ready for use. If my instructions are too brief, you might benefit from Ken Stone’s detailed instructions with lots of pictures.

Two icons representing the two hard drive partitions will appear on your Mac’s Desktop. Go to the Apple Menu, select System Preferences and click on the Time Machine icon (Mac OS X 10.5 or newer is required). Click the Select Disk button and pick your Time Machine and then click the Use for Backup button. Apple offers a succinct introduction to using Time Machine.

After you download and install Carbon Copy Cloner, open it from your Applications folder. In the Source Disk section select your Mac’s internal hard drive which is typically named Macintosh HD. In the Target Disk section select the smaller partition which you created in Disk Utility. Click the padlock icon in the lower left corner and enter your Mac OS X administrator password, then click the Save Task button. In the Scheduler window that appears enter a name for the task in the Scheduled Tasks section. On the right-hand side, in the “Run this task:” section select “When Target  is Reconnected.” Click the Save button in the lower right corner to save this configuration. The developer offers lots of support and instructions for Carbon Copy Cloner.

Carbon Copy Cloner

You have now partitioned an external hard drive and configured Time Machine and Carbon Copy Cloner to backup to each of the partitions. If you follow my recommendation of buying two external backup hard drives then you’ll want to repeat this setup procedure for the second drive. Next week I’ll provide instructions on how to swap between two hard drives and have Time Machine backup to both hard drives.

The focus of this article is to describe the essential components of a comprehensive backup system for your Macintosh computer. This article’s recommendations are appropriate for anybody with between one and a few Macs which they would like to backup. If you have a larger network of Macs, then other applications and approaches would be more appropriate.

I believe that there are two types of people in this world. Those who have lost data and those who will lose data. Thus, I feel strongly about the importance of backing up your computer. A comprehensive backup system will help you minimize the amount of data that you could ever lose.

We all store valuable files on our computer, though what is valuable varies by person. For some it is email messages, calendar data and address book information. For others it is their Quicken or QuickBooks information. For others still it is their digital pictures, home movies and music. For some it is all of these kinds of files. We increasingly rely on computers, so minimizing downtime and recovering quickly from problems need to be incorporated into a comprehensive backup system.

In some ways, a backup system is analogous to an insurance policy. We hope we never need to rely on it, but we’re very glad that we have it if it is needed. Just as different types of insurance policies provide different amounts of coverage, not all backup systems provide the same levels of protection. However, any level of protection is better then no protection at all. Here is a list of the essential components in a comprehensive backup system.

• It should backup all files on your computer
• It should run frequently and automatically
• It should produce multiple backup copies of your files. The old rule of thumb is that if it’s important enough to backup once then it’s important enough to backup twice.
  
• The multiple copies should be kept on multiple disks which are securely stored in multiple locations. One of these locations should be off-site or, if on-site, in a Class 125 fireproof safe.
  
• You need to monitor the backup system at least weekly to ensure that it is making backup copies of your data.
  
• You need to test your backup system a few times each year to ensure that it’s working properly and so you’ll know how to use it to restore a file under pressure when a problem arises.

The Tao of Backup web site does a very good job of describing the importance of each of these components in an entertaining and educational way.

Backup systems allow us to recover from a range of problems that can occur. The most common type of problem is accidentally deleting a file and needing to get it back. Another all to common problem is hard drive failure, in which case we’d need to recover all files. Although rare, burglaries, fire, flood and theft all occur and would require us to recover all of our files too. To recover an accidentally deleted file or to recover from a hard drive failure all one needs is a local, on-site backup copy of their files. However, to recover from a burglary, fire or flood can often require having an off-site backup copy of your data.

While I encourage everybody to setup a comprehensive backup system, I understand that not everybody has the time or money to commit to such a system. I’ll re-iterate that any level of protection is better than none at all and a pretty good backup can be surprisingly affordable.

In more practical terms, here is a simple, comprehensive backup system for one Mac. Start by purchasing two external hard drives. Partition each drive into two parts. Configure Carbon Copy Cloner (donations requested) to make a full bootable backup of your Mac to one of the partitions on each of the external drives. Carbon Copy Cloner can be scheduled to perform automatic backups whenever the hard drive is connected. Configure Time Machine, which comes included in Mac OS X 10.5 and higher, to perform automated hourly backups of all files on your Mac to the other partition on each of the external drives. On a designated day each week you can switch between the two hard drives. The idle drive should be stored off-site at a secure location across the street or across town. If you’re not inclined to buy two backup hard drives then you could supplement your one on-site hard drive with off-site backups made by CrashPlan. CrashPlan is an online backup system. They have different pricing for personal and business use. (I’ve now written Tech Tip articles about using CrashPlan for either personal or business use.)

The reason to use both Carbon Copy Cloner and Time Machine is that even though Time Machine backs up all files on a hard drive, it does not do so in a manner which lets one start (boot) their Mac from the Time Machine backup drive. Thus, Carbon Copy Cloner is a nice supplement to Time Machine since it’s focus is making a bootable backup drive. Having another hard drive from which one can boot their Mac can minimize downtime and can be helpful in the event of problem with the internal hard drive.

Monitoring the system is easy. To monitor Time Machine simply click on its Menu Bar icon to see when it last ran and/or look for its Menu Bar icon to spin while it is performing a backup. When you swap the backup drives you should see Carbon Copy Cloner automatically start.

Apple has an article which provides instructions on how to restore files from a Time Machine backup. Practice this a few times so you have confidence that Time Machine is working and so you’ll be calm if you need to rely on Time Machine for real. An important test of the Carbon Copy Cloner backup is to go to the Startup Disk System Preference, select this disk and then restart your Mac to ensure that you can boot from this backup. To determine which drive was used to startup your Mac, go to the Apple menu, select About This Mac and see which disk is listed as the startup disk or use Disk Utility.

A few final notes. Archives are different from backups and I think you should archive your more important data as well. I’ll talk about archives in a future article.

TidBits’ has written a couple of excellent Take Control PDF books about backing up Macs. Check them out:

Take Control of Mac Backups and Take Control of Easy Mac Backups

This article is the first in a series of articles that talk about Macintosh backup systems including specific products. Check my Tech Tip blog regularly for more articles in my Backup category.