The Leopard Report: What About Rolling Back an Update?
May 9th, 2007I applaud Apple’s decision to build Time Machine as part of Mac OS X Leopard; I really do. Far too few Mac users have any form of backup regimen, and even when things go badly, some of you still don’t learn from your mistakes, so it could happen all over again.
But Time Machine, at least in the form currently described by Apple in its Leopard preview information, has some limitations. One significant shortcoming is the fact that the backup must be stored on another drive, or network share. Why is this bad? Well, as far as backups are concerned, that’s the preferred procedure, of course, and that’s a good thing.
However, what if you install a Mac OS 10.5 update — of which there will probably be plenty — and something goes wrong? What then? Well, in theory at least, you should perform your backup ahead of the update installation. In fact, that’s always a good idea with any major software change, in case you run into trouble.
So, yes, you backup your files on your external FireWire drive, for example, and then install the upgrade. Something goes wrong, and your Mac crashes right and left. What to do?
Well, you could, I suppose, restore your system from Time Machine, to the version that preceded the update. Again, this assumes that you did run a backup first.
But just how would this transpire? It’s a whole lot more involved than just restoring a few photos from your iPhoto library, since we’re talking of a full system here consisting of several gigabytes of data.
And what would happen if, for example, you installed this update on your Apple note-book, while on the road. Now maybe it’s not such a good idea to install updates under these circumstances, since most of you won’t have a backup drive at hand. In other words, there would be no access to your Time Machine files or the backup files you might have created with a different application.
Do you see what I’m getting at?
Now imagine, just imagine, if Apple decided to build into Leopard a feature already available to Windows Vista users? What’s that? Well, it’s known as Previous Systems, which the ability to roll back your system should an upgrade or a driver installation fail to “take” properly. It’s all done from your startup drive, so you don’t need to have another device handy, since the previous system revision is on hand in case it’s needed.
This is surely not beyond Apple’s capability, and it’s a feature that, frankly, should have arrived long ago.
Consider what might happen now if you installed a Tiger security or system upgrade and something went wrong. This is, my friends, not something that’s beyond the ream of possibility. Just take a look at the troubleshooting reports over at MacFixIt, and you’ll see that a fair number of people run into difficulties of one sort or another under these circumstances. These issues don’t just arise with Apple updates. You could, perhaps, install a printer driver, particularly for a multifunction device where lots of system components may be involved, and suddenly you run into a spate of crashes when trying to print a document.
Indeed, there are a number of areas where you could encounter the unsavory consequences of a bad installation process.
So what do you do then? Well, if it’s a peripheral driver you could, I suppose, install a previous version if one is at hand. But what if the older drivers were part and parcel of your original Mac OS X setup? What then? Well, you could grab ahold of your system DVD and just reinstall your printer drivers. But what if you left the DVD at home, and you’re at the office?
Things are far more difficult with a system update, where the only way to revert to a previous installation is to either perform a clean install or restore from your backup — assuming you have one at hand. And that’s not going to be a fast process by any means, even if you could restrict the restoration process to the operating system.
Yes, Apple has invested a lot of time and energy telling us how Microsoft has been working overtime copying the best parts of Mac OS X. It’s not that Apple hasn’t had any qualms about borrowing a few ideas before, of course. When it comes to the Previous Systems feature of Windows Vista, I’m sure Apple could do a far better, easier to use variation.
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I included this in my list of features that OS X should ‘borrow’ from Windows at http://theappleblog.com/2007/01/29/windows-features-os-x-should-adopt/ and was a little surprised at how hostile the reaction was “System restore seems totally useless to me.” “System Restore is evil and should not come anywhere near OS X.” As if Apple couldn’t do a better job with it than Microsoft… isn’t that the whole point of OS X?
That’s curious, Eddie. Maybe it’s just because it is a feature that’s already available on Windows, so Mac users reset it. Too bad.
Peace,
Gene
System Restore, at least on the older versions of Windows, can often be a disaster. I think far more promising are more elegant solutions, one part of which could be Vista’s very cool ability to do file-system level transactions. Anybody familiar with database transactions will understand why this is cool: basically an app can set a moment in time as the start of the transaction, then do a lot of operations on the file system, decide whether they were successful or not, and, based on that, decide whether to “commit” the changes (i.e. make them “stick”). If, instead, the changes in the transaction are “rolled back”, the disk will be left as though nothing had ever happened. I’d love to see this show up in Mac OS X.
Obviously this doesn’t solve all problems (including those with seemingly successful OS updates), but there are other tricks for that. For example, ZFS, which many are hoping will be included in Leopard, can take “snapshots” of the entire disk at any moment in time with basically zero processing or storage cost. This could easily serve as the foundation for seamless undoing of complete OS updates.
This would be great. Our Web host gives us snapshots of our sites in case something goes awry. Haven’t used them yet, but it’s nice to know they’re available.
Peace,
Gene
Ever since Steve talked about Time Machine when he announced Leopard, that’s kind of what I had assumed it was all about – the ability to roll backwards in time, for just one file, or the whole shebang. I don’t know why you would assume that it didn’t. I don’t remember him saying anything that would lead you to make that assumption.
And for those mac users that reject the idea of System Restore, maybe they’re ex-Windows users that got burned by that under Windows and think Apple can do better.
If Time Machine can do what I think it can, then I see no reason why they haven’t done better already!
I’m thinking in terms of doing a restore from a system upgrade or driver installation on one drive. Time Machine requires a separate drive or network share.
Peace,
Gene
But that’s a safer way to backup anyway. Drives fail all the time. Corruption happens, which is one reason why an upgrade could fail. Much safer to just take the necessary files to rollback from another drive. You’ve got no business upgrading a laptop on the road anyway, since if things go wonko, you’re away from your other recovery resources, unless you’re in the habit of luggin’ along external drives, which kinda beg the point of being mobile…
For regular backups, yes, but as a hedge against a problem with installation where you don’t have the second drive available at the moment, a “shadow” version on your startup drive would be quite valuable. Remember, also, that sometimes people will have no choice but to install software on the road, even though a backup isn’t at hand.
Peace,
Gene
Well, maybe that new file system will answer your wish.
@ Gene:
“Right from the start, Time Machine in Mac OS X Leopard makes a complete backup of all the files on your system. That includes your system files, applications, accounts, preferences, music, photos, movies, documents  everything you keep on your Mac.” (from the Leopard page at http://www.apple.com/macosx/leopard/timemachine.html).
Doesn’t that answer your concern about restoring from an upgrade gone awry? Run the backup, install the update, and test. If you don’t like it, go back to the snapshot.
@Grady Hanes: “Vista’s very cool ability to do file-system level transactions”
Isn’t that like HSF+J, where the J stands for Journaling?
@Gene: “Do you see what I’m getting at?”
Sorry, not really. Backing up and restoring will be easier for most people to do (and more importantly to remember to do), but they can’t magically revolutionize what backing up is. Backing up everything to the same hard drive would double the storage requirements, effectively halving your drive spaceâ€â€not to mention being extremely hazardous for your data. Having to install an update while “on the road” should be -exceedingly- rare for most people. In cases where it’s not, those people should already be carrying their backup and utility hard drive with them anyway (mine’s a 2.5″ 100GB in a FW400 enclosure).
Ah, they see but do not hear. Time Machine requires a second drive or network share, something that I already mentioned in the article itself. I’m talking about the ability to roll back an update using a shadow file on your startup drive, so you don’t have to depend on another device.
No, it doesn’t depend on putting all your files on your startup drive, just the relevant system files, and possibly in a special compressed form to reduce wasted storage space.
Do you see what I’m talking about now?
Peace,
Gene
[quote]Ah, they see but do not hear. Time Machine requires a second drive or network share, something that I already mentioned in the article itself. I’m talking about the ability to roll back an update using a shadow file on your startup drive, so you don’t have to depend on another device.
No, it doesn’t depend on putting all your files on your startup drive, just the relevant system files, and possibly in a special compressed form to reduce wasted storage space.
Do you see what I’m talking about now?
Peace,
Gene
Gene, Peace has nothing to do with your response there.
Were that your actual intent, you’d have posted something along the lines of “Well, it’s clear there are different ways of storing things, and in a perfect world, this is how I envision it would be, however that’s not the perfect way for everyone, but hopefully, it will become an option in the future! Peace, Gene”.
Snappy, snobby comments do very little for anyone, especially those who wish to gain repeat readers who are smart, since apparently the ones you have currently don’t meet your requirements.
Not entirely respectfully, but Honestly,
A Denizen of the Internet
I find it unfortunate that you’d rather insult my readers instead of have a meaningful dialog. You never actually addressed anything I said.
But I still say:
Peace,
Gene