[JerryFreilich]

In response to a frequently asked question... I wrote the following discussion of using Time Machine versus SuperDuper for backing up a Mac. These two software programs are both good and reliable but they work in different ways and have different pros and cons. We've discussed this in club meetings more than once. But since I just wrote it down again, I thought I'd post it here. SuperDuper is the "cloning" software I've been using but there are a number of other programs (notably Carbon Copy Cloner) that do essentially the same thing and this discussion applies to them equally.

SuperDuper is available here: http://www.shirt-pocket.com/SuperDuper/ ... ption.html
Carbon Copy Cloner is here: http://www.bombich.com
Time Machine comes free as part of OS X and is in the Applications Folder on any Mac sold within the last 4-5 years.

Using Time Machine:
Time Machine keeps incremental backups but not a complete, bootable, version of your hard drive. What does that mean? It means it keeps a "snapshot" of exactly what your drive looked like each hour of the past day. Each day of the past week. Each week of the past month. And each month of the past year ... until it runs out of disk space. At which point it should (when all works properly) start deleting the oldest backups and continue ad infinitum. Time Machine is best at retrieving individual files. Because it can go back in time, it is particularly valuable for retrieving indvidual files or folders that you had last Tuesday and now they're gone. It also has the strength of running continuously, unobtrusively in the background. You turn it on and forget about it. It's good for people too disorganized to think about backing up. It has one particular weakness... Time Machine does not make a "bootable" clone of your computer. It has a set of multiple snapshots going back into the past. But you cannot hook the Time Machine up to another Mac and have it boot up that computer and operate like your own machine. And it cannot as easily create a "Restore" of all files when your hard disk crashes. It can be done, but it's a bit of a contortion to do it. And of course, if your disk crashes, you are at that point 'between a rock and hard place.' Not a good time for surprises or uncertainty.

Using SuperDuper (or Carbon Copy Cloner):
SuperDuper makes an exact bootable clone of your complete hard disk. What does that mean? It means it makes an exact copy of every file and every folder on your hard disk. Every application, every aspect of the System software. It is complete and perfect in every way. You can take your backup drive to any other Mac, anywhere in the world (so long as that Mac is capable of running the operating system on your clone), plug it in, the disk will spin up and you will be looking at your own home computer exactly as it was when you last backed up. All the files will be exactly as you put them. All the programs will open and run correctly. Moreover, if your computer's hard drive has crashed and become unusable for any reason, you can simply buy a new hard drive, install it in your computer, and then RESTORE the new hard drive from the contents of your backup. SuperDuper does this miracle in about 30 minutes leaving your new hard drive perfect and exactly as it was when you backed it up. The SuperDuper disk volume is "Finder readable." In other words, you can open the SuperDuper disk drive, open the folders there, and drag something you've accidentally deleted SINCE YOUR LAST BACKUP back to your computer's hard disk. But unlike Time Machine, SuperDuper does not keep a "snapshot" of past times. It only has a copy of the very last time you backed up. The other weakness of SuperDuper is that you have to remember to use it! The paid version of SuperDuper (which costs $28) has a "scheduler" in it, so that you can, in theory, leave it running all the time and it will automatically back up your hard drive each night at 2 AM. Many people use it that way. I don't. I'm a fanatic about backing up. I backup each day for sure. And I backup immediately after I've created any large or time-consuming project that I've just saved. After I back up, I turn off the drive and hide it in a safe place. This lengthens the disk drive's life because it's only used a few minutes each day. But I am completely and safely backed up. But if you forget to do this... or can't be bothered... then this method is not for you.

[Stephen Hart]

Excellent overview, Jerry.

I would add a couple of things.

Time Machine does make Finder-readable files. So, for example, if for some reason the Time Machine interface isn't to your liking, you can just find a file on the Time Machine hard drive and drag and drop it. That can be a bit confusing to do because of all the time-labled folders Time Machine makes, but it's doable. If Time Machine is backing up a Mac it's wired to with FireWire or USB, the files are in a folder called Backups.backupdb. If it's backing up another Mac on your local area network, the backups are in a bundle called [shortname].sparsebundle.
As you say, Time Machine does not make a bootable drive. But it's easy, and in my experience, foolproof to restore from Time Machine, using Migration Assistant.
I did this last year when Apple replaced my iMac's hard drive. I plugged in the Time Machine drive, started the iMac. It acted like it was new, and Migration Assistant ran automatically, asking where I wanted to restore from. An hour or so later, my iMac was exactly like it was before. The only thing I had to do was reauthorize Microsoft Office (because it knows that it's on a different drive), and maybe tweak a couple of preferences.
You can switch between different Time Machine drives. I have two that I alternate occasionally.

Carbon Copy Cloner can be set to keep folders of any file it would have replaced when you clone. It's not as smart as Time Machine, though. You have to manually delete old folders or switch to a new or bigger drive. Restoring from a Carbon Copy Clone to a replacement drive can be done either with Carbon Copy Cloner or with Migration Assistant. The advantage of using Migration Assistant for restoring is that you start with a pristine OS X install, so any faulty system leftovers are eliminated. The time it takes for either approach depends on how many gigabytes of data have to be copied. And, of course, if you're moving to a new Mac, you will want to use Migration Assistant because your new Mac might need a newer OS version.

[Richard Serkes]

And in the best of all possible worlds you could use both, which is what I do. Time Machine has saved my bacon more than once when I needed a deleted file so having it running all the time and saving things hourly is great. Then again I have SuperDuper create a bootable clone every morning in the wee hours while I'm asleep. Paying the $28 for the advanced version of SuperDuper with a scheduler is worth it. I don't have to remember to create the SuperDuper clone, it just happens automatically. For the reasons Jerry has stated above, having a bootable clone of your hard drive just makes sense. You never know when your Mac's hard drive is going to go south.

Thanks for posting this Jerry. I just hope more people take it to heart and start doing backups on a regular basis.

[JerryFreilich]

Thanks to both Richard and Stephen for their added remarks. I should have mentioned that, like Richard, I too use both Time Machine and SuperDuper. My backup drives are big enough to be divided into two or partitions (a task easily done with Disk Utility, in your Utilities Folder). One of the partitions is my Time Machine volume. The other is for SuperDuper. I turn on the drive and let Time Machine do its thing a few times a day when I think of it. I do the SuperDuper backup at least once each day. The two partitions show up as if they were separate hard drives mounted on your desktop. That way I have the advantages of both methods. With the modest cost of Terabyte + drives these days, it is not a costly outlay to do things this way.

[Stephen Hart]

I should have mentioned that, like Richard, I too use both Time Machine and SuperDuper.

Me too! (Except that I use Carbon Copy Cloner.)

I have Time Machine running all the time, and occasionally swap drives, so if a Time Machine drive dies, I'm not completely out of luck. I do CCC clones on two other drives, occasionally.

That's my comfort zone.

[Ray Bentsen]

I have Time Machine running all the time, and occasionally swap drives, so if a Time Machine drive dies, I'm not completely out of luck.

An alternative to swapping Time Machine drives is to have a second one running.

I purchased an Apple Time Capsule drive primarily as a Time Machine backup for my MacBook Air, but also use the same Time Capsule as a second Time Machine drive to back up my 27" iMac. (first screenshot)

Of course, I also have four scheduled SuperDuper backups for the iMac, a separate one made each Sunday of the month ... so even if it takes me several weeks to determine a loss, I would still have a good backup. (second screenshot)

[Stephen Hart]

For me, there's a disadvantage of having more than one drive connected. Several apps and OS processes will spin up any connected drives. Photoshop does this, even though I have my Time Machine drive excluded in Photoshop prefs. Each time this happens, the Mac has to wait for the drive to spin up and mount, and that can produce spinning beach balls. More drives therefore means more delay and more noise.

A Time Capsule at least can mitigate the noise, because it can be far from the Mac.

Of course, when solid-state drives get big enough at reasonable prices, these problems will go away. And even hybrid drives could be made smart enough not to spin up just because a process polls the drive.

I've asked some people who should know, and they tell me there's currently no way for the OS to designate a drive for a single purpose, making it off limits to all other processes. Maybe that could be built into the OS, and that would mitigate my concerns. Furthermore, that'd be a safer system, as then a user couldn't accidentally save a file to a Time Machine drive.