Leopard Review: Time Machine

I believe it was an old friend of mine that once told me, “There are two kinds of computer users: those who back up their files and those who have never experienced catastrophic data loss.” It would seem that backing up one’s files is much like exercise: everyone knows that it should be done, but very few make it a habit. Allow me to fabricate some statistics. In 1943, only 3.2% of left-handed Americans backed up their data regularly. That number rose by 1% during the great virus strike of 1957. However, since then, the percentage of people who regularly back up has remained fairly constant. The results are clear: not enough people back up their files!

Considering the importance of file backups, it’s a little puzzling that so few people make it a habit. Granted, the above statistics are among the 19.4% of statistics that are made up on the spot. However, the fact that far too many people are in imminent danger of losing all their precious information remains all too true. Even I have been guilty of this sin. It begs the question, “Why don’t people back up their data?” Well, if you go back just a few precious years (back before I was born), you can understand why!

The price of storage was bloody expensive! As a frame of reference, a 1,000 GB (1 TB) hard drive currently retails for approximately $260 (as of December 18, 2007). Simple mathematics reveals that this works out to roughly $.003 (.3 cents) per 10 megabytes!

Needless to say, the price of electronic storage has dropped quite steeply. If only the same were true for gasoline! For most people with jobs, the excuse that backup storage space is too expensive is no longer valid. The only excuses now are ignorance or a lethargic attitude. People either don’t know how to back up their data, or they’re too lazy to actually do it; such is often the case. Any effective mainstream backup program has to find some solution to these problematic realities. Apple makes a daring attempt with Time Machine.

What's New?

Everything! There was nothing before (in Tiger). Now there is something. That was easy to summarize!

Time Machine is no ordinary backup solution. Until now, most backup solutions have simply copied files from point “A” to point “B”. If you have a filed titled “Letter to Granny” in your documents folder, it should appear in your backup location as well. If you delete “Letter to Granny,” the file should disappear from your backup the next time your backup runs. This is a fine way to run a backup system…in a perfect world. This type of backup system has one flawed assumption: people don’t accidentally delete stuff. However, people do…all the time. Files are inadvertently tossed in the trash or unintentionally dropped into the wrong folder where they are never heard from again.

So, how does Time Machine do things different? Imagine that your hard drive (and the contents thereof) is a sheet of paper. Most backups will create a copy of that sheet. However, Time Machine sees your hard drive as a book, almost as though it has 3 dimensions. Not only can you view the files and folders that are exist today, but it’s also possible to flip the pages through time. That is, you can not only see what your folder contained at the last backup, but you can also zip through time and see what it contained 2 months ago. That way, if you accidentally deleted “Letter to Granny” two weeks ago (prior to your most recent backup), you will still be able to find and retrieve that file.

You may be wondering, “How do they do that without using up a jillion gigs of storage?” While I don’t claim to fully understand Apple’s wizardry, I’ll try to give you a Reader’s Digest version. Your computer contains files. These files are essentially just chunks of data on the disk. By themselves, the computer can do nothing with them. However, the file system contains index files which links to the raw data contained on the drive. The index files tell the computer where the information physically exist, and where it belongs in the folder structure that displays on the computer monitor. When a file is moved from one folder to another, it is only the index file that is altered. When Time Machine makes a backup of the computer, it begins by first making a carbon copy of the main drive and all the data chunks and index files. After that, it essentially backs up index files. If any files are added, it will add those to the mix as well. According to time machine itslef, Time Machine keeps:

• Hourly backups for the past 24 hours
• Daly backups for the past month
• Weekly backups until your backup disk is full

At the end of every day, the twenty-four hourly changes are consolidated into one daily change. At the end of every month, these changes are merged further. Using this method, Time Machine is able to give the appearance of storing everything while managing to remain quite efficient. A time machine backup contains many index files, but fewer actual files that you might expect.

Since Time Machine saves everything, even if you delete it, how does one actually delete files? After all, there comes a time in nearly every computer-user’s life, when it is necessary to delete a file for good. Sometimes the material is sensitive, but at other times, the file one may wish to delete is simply so large (e.g., 4 GB) that it makes no sense to keep it “just in case.” By using Time Machine’s interface, it is possible to delete files (and all backups). However, Apple makes it challenging enough so that you won’t accidentally delete a file and all its backups.

The preferences for Time Machine are pretty simple. Using an iPhone-like slider, you turn on or shut down Time Machine. There are a couple other buttons allowing you to select your Time Machine drive, and select any exceptions that you don’t want backed up (e.g., I don’t back up my Aperture Library).

What I Like

Simplicity. Time machine is about as easy as it gets. It does what it needs to without extensive set up. The options interface is nearly idiot-proof. Once up and running, it does its chores without having to be told. Mac newcomers shouldn’t feel threatened by this technology. Ease of setup and the lack of maintenance requirements means that Time Machine will probably actually be used!

Appearance. Time machine looks cool. Really cool. The screen swoops away. Stars zoom into view. It really has to be seen to be believed. Who but Apple could make it fun to lose a file, only to find it again in the recesses of space?

What Could Stand Improvement

Connections. As I have mentioned before, I have been having a little trouble keeping tabs on my external drives. It seems that half the time they don’t even register as connected. That’s not a good thing. I’m not sure if that’s an issue with Leopard or Time Machine…or both. I don’t care. Fix it, Apple!