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Mac OS X data backup FAQ

If you need technical support for issues after reading this FAQ, please visit my Tech Support page, where I offer fee based support.

This FAQ is divided into several sections.

Short and easy description of backing up

For those who don't need to know why, and just want to get down to business, I've written a shorthand of what's below. And many of your questions are answered below. The most important thing to keep in mind is keep at least two copies of all your data someplace at all times.
If you want to know how to do it the easiest way to recover from, get two external Firewire hard drives* at least the same size as the one you are using on the internal, and Shirt-Pocket's Superduper. Be sure to only leave the backup drive connected and no other Firewire devices at the time of the backing up.

If you don't mind writing down registration codes for all the applications, and risking a few CDs may not be working in a couple years time, just backup your Home folder (your Users -> yourname folder), using Shirt-Pocket Superduper as well. Doing a straight copy from one disk to another with the Finder won't work except for individual document files, which take a fair bit of time to explain where they are.
Backups should really only be done when you aren't using the computer for anything else, and before you install any new software or hardware.

* Firewire was more essential for PowerPC Macs than Intel Macs, because PowerPC Macs can't boot Mac OS X over USB. That said many USB drives come with their own backup software that runs in the background, and can slow down your Mac. If you get one that says it has its own backup software contact the vendor in question to find out how to turn it off, and use your own backup software if you find your Mac is slowing down as a result of the software in question. Obviously check if your Mac has Firewire first before getting a Firewire drive. For a view of common Mac ports, see:

Thunderbolt which is found on some Macs has a thunderbolt icon, and can be adapted to Firewire, but USB can not. Firewire and Firewire 800 can be adapted to each other as well. Firewire is not to be confused with firmware. Firmware is a special software that sets switches on computer chips to operate a certain way.

I'm happy to elaborate on this if you have a specific question, just e-mail me.


Why backup?

It is not a question of if data will be lost, but when. User error, data corruption, hardware failure, bugs in installers all play a part in potential disasters that only a backup can recover from. While you don't have the viruses or worms on the Mac like you do in the Windows world, it should be no excuse to not backup. These incidents can happen at anytime, and frequently without any warning.

User error is the number one cause of lost data. You drag a file to the trash without meaning to, or use a keyboard shortcut used to send a file to the trash, or take a file out of its prescribed location, and the system gets broke. Before moving preinstalled folders or adding files to preinstalled folders, know what files belong where. Ask if you are unsure. And only start moving files once you know your critical files are backed up. In addition, if you lose track of files, and their location, having a backup you know where it exists will help you find those files which you lost. And then there are technicians who either tell the user, or don't tell the user, that they have to wipe the hard drive to isolate the possibility that a system issue observed can be either hardware or software. It is still user error, for not ensuring their data is backed up before the technician has seen the machine, and user error for trusting a technician will always tell them every pitfall of bringing it in to repair. Naturally a technician who doesn't state very clearly that data loss may be required, should be reprimanded for doing so, and should also learn that they should attempt data recovery before doing anything which may cause data loss. Manage your backups so that information isn't lost by accident.

There are many disk utilities which claim to help keep your hard disk in good shape, and some are better than others, but if you don't have a backup, any of them could actually be worse than the backup software to your data as a simple power failure during use of one of those utilities can make the data get lost forever. Data corruption is probably the number two cause of losing data.

Hardware failure. Eventually all hard disks, tape drives, CDs, DVDs, Zip drives, Zip disks, floppies, tapes, and even drive controllers fail. Hopefully most will not happen during the time between now and when you can afford your next computer, but it could happen. Getting an external source to backup your data to will lessen the risk of any one component making your data get lost forever. Whether it is an external hard drive, CD burner, tape drive, or a zip drive, the more backups of your data you have, the better off you'll be. Some will even say an off site backup is a good idea since a disaster could happen to your home or office that ruins the media on site.

And then there are installers which without warning will remove different versions of programs, and in a few cases have been known to remove all the data on the system by accident.

Always have at least two copies of your data at all times. As the loss of one data source due to any of the above failures means you will need the second backup to recover your data.
And one copy should also be in a remote location in case something happens to the home location whether it is theft, accidental damage, or natural disaster.

In the meantime if you aren't able to make the investment in backup software or hardware at least make yourself a hard copy of all your documents by printing them out. While not as easy to recover from as digital backups, at least you won't be trying to create the data from scratch. Though as you'll see below, some options are no more expensive than printing out your documents.

Finally, Apple now has come to terms with backing up: Which is the article referenced by the update both via Software Update and Apple Software Updates page for 10.5.1 it says:

"It is recommended that you backup your system prior to installing any updates."

You can't say you haven't been warned by the horse's mouth anymore.

What method is best to backup?

Note, no one backup method works best for all people. But the important thing is that you do backup, and have some location where information is stored at least twice at all times. The methods described below will vary in usefulness depending on the amount of money and time you have to spend on backup and recovery. A clone has the most up front money to spend but by the same token is quickest to recover applications, and documents without having to write down registration codes (most applications will recover their codes easily from a recovered clone, a few may not). Other means of backup work if you don't have the means to clone, or the money to put up front for a couple external firewire hard drives. Of course if your data just consists of a few CDs of data or less, a CD based backup makes a lot of sense. Just be sure to write down the registration codes regardless, so you don't have to hunt down the proofs of purchase for the various software to reobtain them.

Speed and backing up

Most backup software may be able to multitask, but for the sake of speed, and lack of corrupt files, please only backup your data when your computer is not in use. You can well imagine, an opened file attempted to be backed up, might be in a limbo state when it tries to back it up. Furthermore, it can only backup its last saved state. Unless you have an autosave feature turned on, backup software will typically only save the last saved state before the backup commenced.

See Time Machine section for tips on backing up and multitasking with it.

How to recover when no backup is available and drive becomes inaccessible?

There are occasions, where you might accidently rename or move your home folder, or its contents and find yourself stuck with a default desktop. If it looks like your hard drive is about as full as it was before this happened, chances are, you may be able to recover from this situation using a few simple instructions from Apple.

If one of your home preference files got corrupted, and nothing was renamed or moved, you might be able to go into single user mode (command-S at startup), and delete the /Volumes/your hard drive name/Users/yourname/Library/Preferences/ file to get the desktop to restore itself. Command is the Apple logo key. Once at the prompt, use the unix commands (note if at all uncomfortable with Unix, you should e-mail me first to make sure you understand the directions) of:
ls /Volumes/
(all commands here and below should be followed by the Return key)

to determine what your volume is that your hard drive is on, do a:

cd "/Volume Name/Users/"

, then do an:


, to determine your home folder name, and then a cd "home folder name/Library/Preferences". You'll then be able to at the command line:


Finally at the prompt type:

and the next Return key will attempt to log you in.

Additionally, if you were booted into Mac OS 9, you might have by mistake thought some three letter named files at the root of the directory were trash and deleted those. They are NOT! They are part of Mac OS X. Apple has written this article if you happened to delete the etc or var directories by mistake.

File Vault images can get corrupt, though can be repaired by the procedure outlined by the knowledgebase in Article HT2631.

In some cases if you don't have a backup, you may have to attempt to recover data from your computer first using a data recovery utility before backing up. These exist when no directory repair utility is able to see the hard drive. Those data recovery utilities are not 100% reliable, though should be attempted prior to repairing the directory when the drive is not backed up.

The best that I've seen is Prosoft Data Rescue. Five similarly featured utilities are Boomerang, Cleverfiles Disk Drill, Wondershare Data Recovery, Subrosasoft FileSalvage, and Stellar Data Recovery So taking either Prosoft Data Rescue, Cleverfiles Disk Drill, Wondershare Data Recovery, Subrosasoft FileSalvage, Boomerang's Boomerang, or StellarInfo's data recovery and coupling one of them with a Firewire external hard drive of equal or larger size can recover data. I recommend a larger hard drive from any source that makes hard drives known to be able to boot the operating system you are attempting to restore, such as Otherworld Computing. Others may be given on XLR8YourMac based on compatibility. A full restore should be bootable, but even if it isn't bootable, you should be able to get useful information off if you connect it to a known working Mac or a second partition (link explains how to partition) of that large hard drive. If the machine is able to boot Firewire drives, which includes all Macs able to run target disk mode, it is just a matter of first installing Mac OS X on one partition of the external hard drive, and giving enough space for recovery of all the information from the internal hard drive on a second partition. That means the boot partition for Mac OS X should be at least 10 GB, and should be the same version of Mac OS X you already have installed on your internal hard drive. Use the installer disk which can install Mac OS X on your Mac as my Upgrade FAQ explains. Once you have installed X on the external hard drive 10 GB partition, boot into it with the startup manager (Intel version, PowerPC version), and then install Prosoft Data Rescue, Cleverfiles Disk Drill, Wondershare Data Recovery, Subrosasoft FileSalvage, Boomerang's Boomerang, or StellarInfo's data recovery. Use Prosoft Data Rescue, Cleverfiles Disk Drill, Wondershare Data Recovery, Subrosasoft FileSalvage, Boomerang's Boomerang, or StellarInfo's data recovery to recover information to the second partition you had made on the external hard drive. You can also use Target Disk Mode to mount both your broken Mac, and the external hard drive with another Mac, thus installing Prosoft Data Rescue, Subrosasoft Filesalvage, , StellarInfo's Data Recovery, or Boomerang's Boomerang on the working Mac, and then doing the recover between the unbootable Mac that is in Target Mode, and the external hard drive. If you would like to try these instructions but don't understand their terminology, please e-mail me and I'll explain any terms you need to know.

If you are certain that Prosoft Data Rescue, Cleverfiles Disk Drill, Wondershare Data Recovery, Subrosasoft FileSalvage, Boomerang's Boomerang, or StellarInfo's data recovery, managed to got all your data, then go ahead and try the directory repair and permissions repair on the internal of the broken Mac. If it doesn't make your Mac bootable, but you were able to recover the important data, and restore it to at least two places, an erase and install, or replacement of the internal hard drive is recommended.

If directory repair does not make that internal drive bootable, and you weren't able to recover all your data, then several data recovery companies exist that specialize in nothing but data recovery, but those tend to cost thousands of U.S. Dollars. The only one that is currently authorized to do recovery of data from physically damaged hard drives while still maintaining one's warranty is Drive Savers. A second data recovery company is Kroll Ontrack. If you find another data recovery firm that you think does a good job for less that Drive Savers, please e-mail me.

Backing up user files

A good article on files from the user folder to backup if you choose not to go the clone method below is Apple's Knowledgebase Article 301239
Another article is 106941 which refers to it. Caution Article 106491 as of the writing of this FAQ recommends a manual backup using root account. The use of root is not necessary for backing up, and potentially dangerous!

When discussing backing up user data, remember that means all data in your Users -> yourname folder with the house icon house image with small door, window on top, chimney and 
 triangular roof, also known as the Home folder.

You can find user data for the following applications here:

Home -> Music if you used iTunes.

Home -> Pictures if you used iPhoto

Home -> Movies if you used iMovie

Home -> Library -> Mail and Mail Downloads folder if you used Mac OS X Mail to store mailboxes on your Mac (IMAP and .Mac by default do not, but can be modified, and POP by default does store mailboxes on the Mac, but can be changed. I'm unsure how Exchange works.)

Home -> Library -> Applications Support -> Addressbook for Addressbook application which doubles as Mac OS X's Mail addressbook

Home -> Library -> Calendar folder for iCal calendars
Home -> Library -> Safari for Safari bookmarks and cookies folder

Home -> Library -> Preferences -> for mail password settings

Home -> Documents -> Microsoft User Data for Microsoft Entourage
Mozilla folders in the Library -> Preferences, Documents, and Library folders will store various bookmarks and cookies for certain browsers. And don't forget the Users -> Library -> Application support for additional documents of other applications. Otherwise look at the Users -> Library folder for documents by specific applications. Make sure to have at least two copies of your user data, and applications so that when you go to recovery, if one has worn out, you can rely on the other. The following are tools you can use to make backups of your user files. E-mail me if you know of any other unique folders that need to be backed up for specific applications.

Apple's Finder and Disk Utility (Disk Copy in 10.2.8 and older Mac OS system versions) will burn CDs and DVDs as long as you have enough temporary storage space for the media. Mac OS 9 was the first operating system of Apple's to have built-in CD burning capability. has a backup software that will backup data to Apple's server, DVD, CD, or hard drive in groups of important data sets.
LBackup - backs up user data with a system administrator's point of view.
Other CD and DVD burning software include: Roxio Toast Charismac Discribe NTIUS DragonBurn

In addition, you may backup your user files to the web, through a Mobileme account or just using FTP on a webhost. Two very good FTP programs are RBrowser for non-secure FTP based hosts and Fugu for SFTP based hosts. Or you may use a flash drive, zip drive, magneto optical drive, or even a hard drive to backup your data to. The point is, it is not on your main hard drive as the only source of the data. When sending to a regular webhost your data, use the control-mouse click Archive option on any folders of data you want to preserve. This option which has been available since 10.3, and makes any data you send over the internet easier to retrieve and preserve its attribute information such as which application could open the data. Similarly, when dragging information to a PC formatted media making it an archive file with 8.3 filenaming will make it easier to retrieve in the future. Don't forget if you are going to PC formatted media, to format it FAT32, and not NTFS. Macs can write to FAT32, but can't write to NTFS unless you add Macfuse, Tuxera NTFS, or Paragon NTFS and HFS Windows to your Mac. Allume's Stuffit Deluxe offers older operating systems a way of archiving files for storage over the web in a platform independent manner. When using FTP to transfer these archive files over, it is best to use a binary transfer. Some webhosts require you use Active versus Passive FTP for transfer. Check with your internet service provider if they offer these options, and how much space they offer. If it is insufficient, check Compare Webhosts to find one that meets your needs.

Making a clone/mirror/duplicate backup

The ideal backup is a clone, also known as a mirror or duplicate backup. Be sure to only leave the backup drive connected and no other Firewire devices at the time of the backing up. Note, these backups do have one serious weakness, and that's when they are done when something else is running which may be changing preferences or caches of important files. You also want to make sure the drive you are backing up to is formatted Mac HFS Extended (HFS+) if using Mac OS 8.1 or above. On Intel Macs, your clone drive needs to be formatted GUID (link explains how) through the Options button under the partition section of Disk Utility to make the clone bootable. On PowerPC Macs, your clone should be partitioned as Apple Partition Map. If doing a dual PowerPC/Intel Mac backup partitioning, see the instructions on Macosxhints. You can network Windows PCs with Macs while keeping the Mac formatting on your external hard drive, using Apple knowledgebase article HT1627 as a guide. Clones will not work to FAT32 or NTFS partitions.

You do NOT want any other application to be open when running such a backup. Also disable Spotlight (in 10.4 only) on your destination drive using Apple menu -> System Preferences -> Spotlight -> Privacy to add the destination drive to the pane. If possible, boot into safe mode to perform the backup (holding the SHIFT key at startup). In addition, you can clone while logged into another administrative user that you don't use at all to avoid further complications of changes which may be happening to your regular user (though don't use Fast User Switching to get into that other user, since that other user is still active when fast user switching is used). Otherwise you are going to be running a backup on a live system which could have changes happening while you are attempting to backup. These may yield an imperfect clone, with uncertain success at recovery. It may be possible that your clone will have its own hardware issues, so make at least two copies. As data corruption may exist in your clone, when you go to recover from your clone, you may find it best to use the Apple Migration Assistant after installing the operating system on the original. Since Mac OS X is bootable on Firewire in PowerPC Macs (Intel Macs support both some Firewire and some USB 2 drives), here is my link which lists external hard drives that are known to be safe with 10.3 and above. Some drive manufacturers haven't updated their firmware to make their drives compatible with 10.3.

Backup software which makes duplicate (also known as clone or mirror backups). These backups will boot any system that is capable of Firewire target disk mode, as that was another one of the features those systems got. To ensure that a clone works, select the destination drive in the Finder, by clicking it once, and selecting Get Info in the File menu, and uncheck "Ignore Privileges". If your clone is successful, then it should be able to boot the same system.
Important Note:
Cloning to another computer via Target Disk Mode is NOT recommended. Apple's drivers are system specific, even with universal installs. Attempting to clone from one Mac model to another of a different vintage or model name, can result in kernel panics on the clone.

Bootable backups on Firewire machines that are older than Apple's official listing of capable machines now are possible through Firewire with the use of XPostFacto according to XPostfacto's website. I haven't tested this yet, but this is an encouraging development for people wanting to clone backup their systems on older Firewire built-in Macs. These are five software titles which I've tried that are able to make a clone backup: LaCie's SilverKeeper is no longer listed on their website, but was a backup software for older Macs. 's Retrospect Express and Desktop Carbon Copy Cloner. Note, if you use older versions Carbon Copy Cloner, be aware that an incomplete backup could yield a huge temporary file in the /Volumes direcrory. This is covered in more detail on Bombich's discussions. SuperDuperDescription.html Superduper

Apple Disk Utility (included with 10.3 and above)/Software Restore procedure written by someone at Bethel College. I've also written a procedure on my Cloning with Disk Utility FAQ which has only been tested on 10.4.2.

Software which I haven't tried yet but also says it can do a clone backup: Tri-Edre Cloner. Tolis Group - Cloning and crossplatform backup software developer. Synchronize Pro Deja Vu Backup Simplicity Data Backup Copycat
Diskology's mass disk duplication systems

Time Machine

Apple's Leopard (10.5) operating system released October 26th, 2007, and Snow Leopard and Lion operating systems have a feature called Time Machine. Time Machine's behavior is not quite what is expected, but once you understand it you can make full use of its capabilities. In this page: it says:
"Backing up to a full disk. One day, no matter how large your backup drive is, it will run out of space. And Time Machine has an action plan. It alerts you that it will start deleting previous backups, oldest first. Before it deletes any backup, Time Machine copies files that might be needed to fully restore your disk for every remaining backup. (Moral of the story: The larger the drive, the farther back in time you can back up.)"

Turns out you can turn on that warning, or turn off that warning, but it makes no difference, it will go ahead and start to delete hourly backups more than 2 days old! So you are better off making sure that you don't delete files more than once a day, and that way, you won't lose information to time machine's need to keep disk space clear on the backup. It falls somewhere between having a clone, and just data backup, as it makes a restorable system on its own without having to lose critical information from preferences like simple User Data backup solutions do. From all appearances, it saves all the important information to rebuild your machine if you keep a copy of Leopard handy. This does pose a problem if your Leopard DVD should fail. I strongly recommend following the steps on my Make a bootable CD FAQ using a DVD+R DL discs to make a Leopard DVD copy so that if your existing Leopard disc should die, you'll have another you can restore your Time Machine backup with. Not all Superdrives are DVD+R DL compatible. Visit Otherworld Computing, or Patchburn, and XLR8yourMac if you find yours does not have an entry in Apple menu -> About This Mac -> More Info -> Disc Burning -> Hardware -> Disk Burning -> DVD Write where it should say +R DL showing that your drive supports it. If it doesn't then adding an external Firewire DVD burning drive using these sources as references and/or places to purchase it, will allow you have a drive to make that boot DVD of Leopard copy.

Special thanks to Macworld from Apple Discussions, we now have directions for remote backup via ssh using Time Machine:
/System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd-helper &

Is it a good enough reason to upgrade to Leopard? These Upgrade Steps still apply regardless of whether it is, or isn't.

Lastly, it is important to remember since Time Machine functions in the background when turned on via Apple menu -> System Preferences -> Time Machine, you are better off leaving it off, and manually turning it on via the menubar icon for it when you are not going to use the computer. Check the menubar icon for it to determine if it is backing up before trying to multitask with your backup.  

Lion Data Recovery

With Apple's July 20, 2011 Mac OS X 10.7 Lion introduction, Apple has released a new form of data recovery. Described in full detail on Apple How To Knowledgebase Article 4848 A small bootable partition gets installed when you install Lion that includes the basic tools found on the 10.7 installer Flash drive. While not as foolproof as having an external hard drive, it does offer some ability to recovery the system to its base install, and recover data from any external backup you might have made with Time Machine or a cloned system. It does not stop the need to etiher make a Time Machine or Clone backup.

Unlike Time Machine with earlier versions of Mac OS X, it no longer requires there be a system installer to restore the Time Machine Backup. However, those who backed up systems older than 10.7 trying to recover Time Machine backups in 10.7 or later may run into issues, especially if they don't have the 10.6 installer disc or older, and if the software required the use of Rosetta. For more on Rosetta, and why this matters, see my tip on Apple Support Communities.

Using the Migration Assistant for cloning purposes

Note due to the reliability of booting off a Firewire hard drive being less than that in some situations than that of booting off an internal hard drive, the first method described below is not recommended unless you are certain it is worth the risk. You'll see also below it see a better method of recovering data from a clone. If you should lose your connection in the middle of booting off an external hard drive, while trying to import data to it, both the boot data on the external hard drive, and the data being transferred while the connection is lost could be compromised. On the other hand, if you lose your connection while booted off an internal hard drive, the boot system of the internal hard drive won't suffer the same compromise as it isn't being actively used by the external hard drive, and then only the data being transferred could potentially be lost. As always, it is recommended you have at least two copies of your data at all times! Here's the method:

1. Install the operating system (you may need to create a different primary username which you can later erase for the migration assistant to work properly)
to an external hard firewire hard drive (note these limitations for external Firewire hard drives)
2. Boot off the external hard drive.
3. Apply the updates to the external hard drive of Apple operating systems, and security updates keeping in mind these precautions.
4. Migrate the data from the internal drive to the external drive with The Migration Assistant.

The Migration Assistant does work better if you are recovering from your backup, as you would run:
1. Erase a new internal hard drive.
2. Install (you may need to create a different primary username which you can later erase for the migration assistant to work properly)
and apply the updates to the internal hard drive of Apple operating systems, and security updates keeping in mind these precautions to get your hard drive up to the level that your backup was at.
3. Migrate data from your clone with the Migration Assistant after connecting an your Firewire hard drive clone.

The first book that I've seen geared towards teaching how to backup Mac OS X has been released by Tidbits Take Control of Mac OS X Backups by Joe Kissell.

Suggestions? Please e-mail me

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