How-To: Computer Backup and Data Safety

Last update: 30 April, 2013

This topic is relevant to all computer users, but since this is a photography-related site, let’s put this in a photographic perspective. Say you were on a photo tour where you carefully managed your memory cards and made sure your images are safe. You shot some great images, edited them to perfection and in two hours friends and family are coming over for an exciting photo presentation. But when you turn your computer on all you see is this:

Error 1308: Hard-disk failure. No boot device available. |

Oh, no!!! You meant to make a backup all this time, but you had more important things to do, didn’t you?

Fortunately the above was just an imaginary scenario, but keep this in mind:

  • If disaster can happen, it will — probably some day when you least expect it.
  • Disk space is cheap, but your computer data is very valuable.
  • People tend to forget or turn lazy, so prefer automated solutions.


Backup Commandments

  • Backup everything (system, data, applications, settings) and prefer a bootable backup. This way when disaster strikes you can boot from the backup disk and repair the damage in no time.
  • Backup often. In fact, backup every time you think to yourself “Now that I’ve accomplished this important task I sure don’t want anything to go wrong.”
  • If you make just one backup, keep it separate from the original. If a burglar broke into your home and stole everything of value, you’ll surely be happy to have a backup off-site. Even better: make two backups and keep one hidden at home and the other off-site.
  • Keep (some) older backups, just in case you don’t immediately notice when your hard-drive starts turning flaky or a virus slowly corrupts your data. As a minimum keep a backup from yesterday, last week, last month and last year.
  • Check your backups occasionally and rehearse the restore process. Otherwise you might experience some unwanted surprises when disaster strikes.
  • Encrypt your backups. With several copies floating around your data is safe, but only as long as no one else can read it.

And the very last principle?

  • If you’ve been procrastinating until now: start today!


Basic Decisions

  • Medium:
    • CD / DVD are not recommended: the longevity is not great, the capacities are too small compared to modern hard drives, and you are producing lots of harmful waste.
    • 3,5″ external hard-drives are very cheap and reliable, and have high capacities. But they are relatively large and heavy, and always require an AC connection.
    • 2,5″ portable hard-drives are great: cheap, light, easy to use and carry around. In mid-2013 you can buy a 1TB disk for less than 70 EUR and 2 TB for 130 EUR. Among the different computer interfaces USB3 seems to be winning out, followed by USB2 and FireWire. eSATA drives are also popular, but they are normally not bootable, which is a serious disadvantage.
    • Specialized storage devices (RAID, Drobo, etc.) allow you to attach several hard-drives and configure them in series (for more space) or parallel (for faster access). They are extremely reliable, but also large, expensive and usually attached to a network. This makes them very convenient for easily-accessible backups, but apparently impracticable for using on the go or for storing off-site.
    • “The cloud”: This topic is quite controversial because you place your data in the hands of a third party.
      • Advantages: off-site storage, automated solution, synchronize data between multiple computers, professional provider ensures secure and redundant data storage of current and older versions of your data.
      • Disadvantages: data access can be slow, security concerns (“Is my data still there?”, “Who else has access to my data?”, “How long will this provider stay in business?”), requires a working computer and Internet connection for data recovery, high cost (up to 20 times the price of a comparable hard disk), limited bandwidth at the end of the month (depending on chosen price scheme).
      • See [2] and [3] for a list of cloud-storage providers and prices.
  • Creation Methods:
    • Complete: always copy the entire content. Naturally this takes a long time, but all methods start with a complete backup. Some people make only complete backups because the algorithms are extremely simple and reliable, but on the other hand the massive amounts of data are stressing both drives significantly and (some say) wearing them out prematurely.
    • Incremental: only copy the data which has changed since the last backup. This requires at least one complete backup first, but thereafter it is much faster. The disadvantage is that an incremental backup relies on the integrity and completeness of all previous backups.
  • Backup Methods:
    • A bootable clone is an exact copy of the original hard-drive.
      • Original and clone are completely interchangeable, so your data is immediately available, without a time-consuming “restore” step. Furthermore in case of an emergency you don’t need a working hard-drive to restore onto, so you simply:
        • Connect the external backup drive, boot from it and continue working. In the next days buy a new drive and replace the failed internal one. Connect the external backup again, boot from it, then clone its contents onto the new internal drive. This involves the least amount of hardware interaction and places the new hard-drive in exactly the right place — as primary disk inside your computer.
        • Less optimal would be to take the backup drive out of its enclose, place it into the computer and continue working. In the next days you buy a new drive, place it into the backup enclose and clone the internal drive onto the new backup drive.
        • If your entire computer is damaged or stolen, you could even attach the backup drive to a different computer, boot from the backup and continue working. As soon as you repair or replace your primary computer, attach the backup drive to it, boot from the backup and clone it onto the new internal drive.
      • The initial creation of a bootable clone is time-consuming (complete backup), but after that clever backup programs are able to update an existing clone with only those files that have changed (incremental backup).
      • The main disadvantage of bootable clones is that they don’t store any “history,” so you can only restore the newest version of your data.
    • A disk image is a compressed copy of the data on your hard drive that can be updated incrementally, so it may sound like a good backup solution. However it has a number of disadvantages, which make it less attractive than a bootable clone:
      • The data is not directly readable, so you need a lengthy data restore.
      • But disk images are also not bootable, so you need a way to boot your computer before proceeding with the recovery.
      • And if the internal drive fails completely, you need a new drive to restore onto.
      • Finally, disk images don’t store any “history,” so you cannot restore older versions of your data.
    • Backup methods with “history” make a snapshot of your data each time you make a backup. The first time they perform a complete backup, but after that they only store the files that have changed (incremental backup). Such backups are not bootable and require a lengthy restore operation as well as a working drive to restore onto, but they are extremely helpful because you can recover newer or older versions of your files.
      • Backup solutions of this type (for example Apple’s TimeMachine) are highly recommended for inexperienced users.
  • Redundancy and Frequency
    • The more copies you make, the higher the chances that at least one of them will save you in case of disaster. And the more often you make a backup, the higher the chances that the recovered data is up-to-date.
    • However don’t overdo it. If you start out too ambitiously (too many copies or too often), you probably won’t keep it up for a long time.
  • When to backup in a photographic workflow?
    • Burn all new images on a DVD. Not a great idea because (1) as described above we don’t recommend DVDs as a backup-medium and (2) backing up all images from a shoot on a write-once media is a major overkill. How many of those originals are you ultimately going to keep? For us at photographically curious that number lies under 25%.
    • Immediately after importing images from a memory card. Not a bad idea (unless you are backing onto DVDs), but it should not be the only time you perform a backup.
    • Backup after completely editing a group of images. Also good, but it should not be the only time you perform a backup.
    • Ignore any photography-related events and just backup every X hours or days. This is probably the best idea of all, because it’s very simple and can be automated. Choose the backup frequency based on your personal failure tolerance.


MacOS Workflows

Built-In Solutions

MacOS contains a very convenient and robust set of tools for creating backups and restoring from them as well as for booting even when your system partition is damaged.

  • The Disk Utility allows you to create or restore a complete image of your entire hard drive. There is no support for incremental updates and no automation of any kind, so the process is manual and time-consuming. Still, if all else fails, you can achieve some safety this way.
  • Time Machine is an integral part of the MacOS since 10.5 Leopard. It backs up all drives of your Mac onto a dedicated external drive automatically and without interrupting or interfering with the user’s actions. The drives can be directly attached via USB, FireWire, eSATA, network or via AirPort. The first backup is complete, all subsequent ones incremental. By default Time Machine creates a new backup every hour and keeps all backups from the past 24 hours, a backup for each day of the past month and one for each week before that. When the backup disk runs out of space the oldest backups get deleted.
    • If the backup drive is formatted as MacOS Extended and encrypted, all backups are automatically encrypted.
    • Using a very intuitive graphical interface, Time Machine makes it very easy to recover a version of one or more files from any of the backup snapshots.
    • MacOS Recovery makes it very easy to restore your entire system from a Time Machine backup.
    • If you make a Time Machine backup on one mac and restore it on another, you have effectively transferred all your settings, programs and user data. This is especially useful if you buy a new computer and don’t want to reinstall and set up everything manually.
    • Since MacOS 10.8 Mountain Lion Time Machine can perform independent backups onto different drives.
    • Time Machine can be configured to ignore a list of user-specified directories (those that hold logfiles, temporary or cached data).
  • Your Mac ships with a special disk partition which allows you to boot up even if your system partition is damaged. To get to it hold Command-R while your Mac is booting. Once in the MacOS Recovery you can:
    • Start the Disk Utility, format your internal drive, then restore from a disk image created previously.
    • Restore from a Time Machine backup.
    • You can even download a clean operating system, then restore from a backup.

Even though Time Machine and the MacOS Recovery require a separate recovery partition, a time-consuming data recovery and a working hard drive to restore onto, they are great tools and sufficient for 95% of all Mac users.

Third-Party Solutions

Mac users who need a backup strategy with almost zero-downtime can use SuperDuper! or Carbon Copy Cloner to create bootable clones (see above). Both programs are commercial, but cost less than $40 and are highly recommended.

Both programs can also create disk images, but as discussed previously, these are not optimal for data backup.


Minimal workflow

  • Buy a 1 or 2 TB 2.5″ external drive and format it using Mac OS extended, journaled, encrypted.
  • Turn on Time Machine and tell it to use your backup drive. Time Machine creates a complete backup of your data.
  • (A) If you keep the drive constantly connected to your machine Time Machine will make backups every hour. This is great because you never lose more than an hour of work, but since the drive lies next to your computer, you are not well protected against theft, fire, etc.
  • (B) Keep the backup disk separate from your computer. Attach it daily, let TimeMachine make a backup, then stow it away again. This increases the amount of potential data-loss, but increases the chances that the backup drive remains intact in case of burglary, fire or flood.

Recommended Workflow

  • Buy two backup drives.
  • Use the first one exactly as described in “Minimal Workflow”.
  • Use the second drive in a very similar manner, except keep it at a different location (in your office, in a friend’s house, in a bank vault). Bring it home between once a week and once a month, make a backup, then bring it back.

This method immensely increases the likelihood that one of your backups will survive almost any disaster, but you still have to worry about booting up and performing a time-intensive data recovery. On the positive side, you don’t have to buy and learn to use any additional software.

Ultimate Workflow

  • Install SuperDuper! or Carbon Copy Cloner on your Mac.
  • Use two backup drives as described in “Recommended Workflow,” except …
  • … instead of using Time Machine on the second drive, make a bootable clone with SuperDuper! or Carbon Copy Cloner.

By using two different methods from two different software companies on two different drives stored at two different locations, you reduce all risks to virtually zero. Furthermore a bootable backup gives you the possibility of an almost zero-downtime recovery.


Windows Workflows

I need help from someone knowledgeable about Vista, Windows 7 and Windows 8.

TODO: general discussion
20121231-10107931010793TODO: suggested workflows

Comments? Questions?

This article is supposed to grow and turn into an Internet reference page on backing up your computer data. If you notice any errors or omissions, or if you have any questions, don’t hesitate to contact us or post a comment below.

Appendix A: Further Reading

  7. SuperDuper!
  8. Carbon Copy Cloner