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The art and science of OS X system upgrades

tiger boxSince 10.2 (or was it 10.1?), we Mac users have had to make a choice when it comes to major ("dot release") OS X releases: how will we upgrade? In its current incarnation, the OS X installer offers three options:

  • Upgrade Install: The easiest option for users, this simply patches the necessary bits of the system and bundled applications to migrate from the current OS to the new release.
  • Archive and Install: The installer moves the entire current system, Users folders and all, into a Previous System folder, and then installs a new copy from scratch. You can optionally migrate over your Users folder to ease the transition.
  • Erase and Install: The "wipe the slate clean" approach. Your hard drive is erased, a new system is installed, and you start over from scratch.

Which method to use is seemingly a matter of great debate. Apple has a good overview available, too, with a brief description of each option.

Having just recently started (note that it's not yet completed) migrating my primary boot drive to 10.4, read on for my thoughts on upgrade strategies, the strengths and weaknesses of each of these methods, and which I prefer (and why).

General Upgrade Advice

Before I discuss the particulars of upgrading an OS X installation, here's some general advice that I always follow when undertaking a major upgrade like this. Note that some of these steps can be quite time consuming, but since there's no going backwards from an upgrade, I feel they're worth the time. There's also a level of overkill in here, but my data is my livelihood (in both my job and my website 'hobby'), so the redundancy helps me breathe easier during the upgrade.

  1. Run Disk Utility's Repair Permissions. I'm not one of those who thinks this is a magic solution to all problems, and I don't usually run it very often. But I always make a point to run it before starting a major upgrade, just to make sure things are as Apple intended.
  2. Make a boot disk backup. Not your entire hard drive, just clone the system itself onto a bootable disk. That way, you'll have an old version of the system, just in case things go south. I have a spare 40GB partition set aside just for the old version of OS X, and I clone to it before a major upgrade. I've been using Carbon Copy Cloner (CCC) to make my clones. Note that CCC hasn't been updated yet for Tiger, so if you're trying to clone a 10.4 disk, you'll need another solution. SuperDuper has been recommended to me, though I haven't tried it yet.
  3. Test your boot disk backup. After creating a bootable backup, set it as the startup disk and make sure it works.
  4. Back up your critical files. Note that this doesn't necessarily mean your entire hard drive. In my case, I don't back up my applications, nor do I bother with my Downloads folder or my Installers folder (with the exception of a "No longer available" folder of old installers I keep around). I focus on my data, as that's the stuff that's not replaceable if I were to have a crash. I use a 200GB FireWire drive for these backups, and it's only connected and powered on when I'm writing to or reading from it. Other than that, it's off and not connected to anything. I use a free program called Silverkeeper to create backups of these files. It lets me easily set what to back up and when, and seems to work well. You could, of course, just copy them in the Finder if they're all user-level items.
  5. Back up custom Unix-level stuff. I'm not a big Unix power user. Still, there are a few things on my machine that I'd hate to lose. My Apache configuration file, for one. My local copies of my sites for another. And the MySQL databases that drive those sites. So I take some time to back these up separately, even though they're on the cloned drive, too. I use the same FireWire disk and Silverkeeper to do these backups as well. If I'm really feeling paranoid, I'll also use MySQL to export my databases to SQL files, and back those up.

Which Upgrade Method to Use

With the preparatory work out of the way, it's time to upgrade. But which method should you use? I have my favorite, of course, but first, let's look at the strengths and weaknesses of each method.

  • Upgrade Install: This is by far the easiest method, and it's the one that's recommended for most OS X users. I don't actually dispute that advice -- it's what I tell my mother and friends to use on their Macs, for instance. But it's not for everyone, myself included. Why not? Let's start with the pros and cons, and then I'll explain my thinking.

    Pros Cons
    Very easy to do Leaves all third-party extensions installed
    Lowest chance of data loss Modified applications may not be updated
    Upgrade that requires the least pre-work System stability may be an issue post-upgrade

    OK, so why don't I run upgrade installs? If you're the type who tweaks OS X (perhaps by applying many of the hints from, you may have issues. As a real-world example, I tried (for the first time ever) an Upgrade install on my PowerBook. When I was done, things seemed OK at first. Then I tried using the Calculator. It worked OK in basic mode, but the different View modes were shot -- all I got was a big blank metal window. After some digging, I figured out that it was because I had applied this hint to enable other Calculator modes. To get Calculator working again, I had to go copy a "clean" version from my G5's 10.4 partition.

    The other downside to an upgrade is that if you like running all sorts of system add-ons, you may wind up with an instable system when all is said and done. Although the upgrade on the PowerBook seems good at first, I soon began having troubles -- the Finder would quit, I occasionally couldn't launch Safari, the SystemUIServer (menubar) restarted spontaneously, etc. To what do I attribute these issues? I'm not sure, but I suspect one of the many extensions that I have in the menubar may have been at fault. GeekTool, MenuMeters, Salling Clicker, Butler, and a couple others I don't recall all lived up there. So even though the OS had been upgraded to 10.4, I hadn't yet checked the extensions for compatibility.

    In the end, the PowerBook wasn't really usable after the upgrade. Despite my disabling the extensions, trashing preferences, etc., I couldn't get rid of all the problems. So I decided to start over fresh, and ran a Erase and Install (more on that later).

  • Archive and Install: This is, at least in theory, just like doing an Erase and Install. When done, you'll have your new system and a folder with (most of) your old system, allowing you to somewhat easily retrieve pieces you may need. The old system isn't bootable, due to changes the installer makes to it during the install process -- as one example, the top-level /Library/Application Support folder is moved into the new system. Here are the pros and cons of this method as I see them.

    Pros Cons
    Third-party system extensions are not copied over Takes the most disk space
    Automatically creates a backup Manual work may be required to clean up after the install
    Installed third-party applications remain in place Takes a long time to run

    For the first time ever with 10.4, I tried an Archive and Install (have a sense now of which method I prefer?). I chose to try it on my G5 at home, reasoning that the time saved over an Erase and Install would be worth it. In the end, though, I haven't saved any time, and I don't think I'll use this method again. Note that this is my experience, and not necessarily a recommendation.

    For me, the troubles started when I told the installer not to copy over my Users folder. My rationale for this is that I didn't want to bring over all my prefs and everything else in the Library -- that's where I install my menubar extensions, for instance, and I didn't want them brought over. So after the installer finished, I created a new "me" (ah, if it were only that easy in reality), and then started bringing over those certain prefs and extensions that I knew worked in Tiger.

    What I failed to take into account, I think, was that certain applications also put their stuff in the user's Library, causing various issues. Motion, for instance, failed to launch. Despite my best efforts with Spotlight and moving folders, I couldn't get it to load. So I pulled out the installer and reinstalled. Motion now launched, but would crash out after the splash screen. What I found odd was that Motion was still version 1.0.1, even though my CD is only version 1.0. So I then manually trashed everything about Motion that I could find, including the application itself, and ran the installer again. This time, Software Update came up and offered the Motion update, and the program ran fine after that. I now have to investigate the rest of my apps -- most will work fine, I'm sure, but some will require some futzing. So in the end, this method isn't going to save me any time over my usual preferred method.

  • Erase and Install: Often times called a "clean install," this is my preferred upgrade method. It's also, by far, the most work, so it's not for everyone. When you use the erase and install option, you get exactly what's described: an erased hard drive with a brand-new, factory-fresh OS X installation. Here's what I see as the pros and cons of this approach.

    Pros Cons
    Finished product matches factory-fresh machines Requires a lot of pre-install work
    Every application is brand spankin' new Has the greatest potential for loss of data through stupidity
    It's the quickest install, after the setup work Requires a lot of post-install work

    Given the infrequency with which major OS X updates are released (roughly yearly, though the pace will be slowing now that Tiger is out, or so Apple has stated), I find the amount of work needed for a clean install to be bearable, given the benefits. However, there is the possibility of doing something really stupid to cause data loss, as you are moving gigabytes of data back and forth. One little mistake of dragging "from" and "to" in the wrong order, and you could find your data gone -- multiple backups are a good thing.

    I like the erase and install option as it gives me a good chance to clear out the cruft that accumulates between major releases. There is something about my machine, however, that makes this process a bit simpler for me: the vast majority of my data files and applications live on separate partitions. My Documents folder holds only my web- and magazine-related stuff; everything else is on a Data partition. Video work has its own partition, so there's nothing in Movies. Music lives on its own MP3 partition. There are pros and cons to partitioning, of course, but ease of major upgrades is one of the biggest pros from my seat.

    After the bad experience with the PowerBook's upgrade install, I took it home for some major surgery. I plugged in the FireWire drive, backed up everything, then did an Erase and Install. After copying my data back over (but not my User environment), reinstalling some applications (and simply copying some others), the machine was ready to go. It is, however, a time-consuming process when you consider the pre-work and post-work required to bring things back to a usable state. Reinstall every third party application, every font, every system extension, etc. This method is not for those who are pressed for time!

    Since the clean install, the PowerBook has been rock-solid stable and I've had no issues with it at all. I may wind up doing this on the desktop machine as well, if I have too much trouble with the applications and stuff brought over in the Application Support folder. Only time will tell...

Conclusion and Recommendations

I appreciate that Apple offers three different installation options -- judging by the new poll on the hints site, it seems that all three methods are getting use (it's early in the poll process; I just posted it an hour or so ago). Based on my experiences, and reading about others, here's when I think each method should be used:

  • Upgrade Install: If your haven't modified your stock applications and you don't have a bunch of customized Unix stuff installed, this method should work fine. For most "typcial" Mac users (note -- I don't think most people who read hints fall into that category!), this is the upgrade method of choice. While you don't need to implement every step of my paranoid pre-upgrade ritual, it's vitally important that you back up key data files before starting -- you never know what's going to happen during an upgrade.
  • Archive and Install: If you'd like the benefits of a clean install without all of the work, and have the drive space, this is the best option. Similarly, if you have a bunch of Unix stuff that you want to keep around, this is a good choice, as you'll be able to find it in the Old System folder. I would recommend letting OS X bring over the Users' settings as well, and then just cleaning out the unneeded stuff. My method of doing this the other way around doesn't seem to be worth the effort. Again, back up first!
  • Erase and Install: If you've got the time, the drive space, and the motivation, I really do think this is the best option. It forces you to take a look at everything you've got running on your machine, and decide just how much of that stuff to reinstall. It does take time, and you want to be very careful that you don't overwrite backup files when moving the data back onto the clean machine, so there are downsides.

This entire piece is, of course, my opinion based on my experiences. I welcome your thoughts, and hope that one point made it through most clearly: regardless of how you choose to upgrade, please back up your important data beforehand!


13 thoughts on “The art and science of OS X system upgrades”

  1. My suggestion is to try the "Upgrade" option first. If for some reason the upgraded system isn't to your liking, you can always wipe it clean, reinstall, and migrate your backup.

  2. I've always just done an Erase and Install. I like to give a new operating system it's best shot at stability. I if there are bugs after the install then it is easier to track them down to a specific application or to the new system. It would drive in insane if I never knew if an odd quirk was because I had conflicts from an Upgrade, or if It was just a fluke or whatever.

  3. Yeah, I generally opt for the Upgrade at first. I like the immediacy of getting to check out the new OS and familiarize myself with what may have changed. Since I use my machine for work(what else?) I find this to be the least painful to get up and running again - The Tiger upgrade took about an hour on an old G4 tower of mine.

    That said, I agree it can really lead to instability with the system. I do have various Unix software and hacks employed which will inevitably start to fight with Apple's default install. I generally plan on doing a clean install a few weeks after I do the Upgrade. This gives me time to check that I've backed up critical data and get my software installers in order. This just gives me the least amount of pressure and hassle in the short term; I can benefit from the new OS immediately, and I can clean out the system and get my mind into the frameset of starting over soon after.

  4. Maybe I didn't catch it, and since this is my first Mac OS upgrade (new Mac user as of a year ago):
    What steps other than what was in your "General Upgrade Advice" (which you should always do) should I take to ensure a safe and 'clean' Erase and Install? From various users' advice, I am planing to Erase and Install, but I'm not sure what to do other than regular maintenance (with applejack[1]) and backing up to my firewire.

    Thanks in advance!

    [1] applejack: - a troubleshooting assistant that runs in single user mode

    PS: I believe this is the best way to say this: THANK YOU for Mac OS X Hints, it is a GREAT resource!

  5. A couple of small additions:

    1. Apple's Disk Utility can make a clone of a disk. It works in Tiger as well as Panther. It's a good idea to disable Spotlight on the target disk before doing this (via the Privacy tab in Spotlight's system preferences).

    2. Another install alternative: Doing an erase and install and hook up the firewire drive with the clone of your Panther system. When the Migration assistant asks if you want to move settings from another computer, say yes and point it to the firewire drive.

  6. I found the whole process incredibly frustrating. No strange rto upgrades/reinstalls (I've done loads on Windows), I initially tried an upgrade install but had stability problems so then did a full "zap and reinstall" - still had some problems so tried it again and this time appear to have a stable install on my iMac G5 - no idea why it should take 3 attempts and doing the 3rd makes no logical sense, but it does appear a lot more stable!

  7. I have always used an archive and install, this is the easiest one to do. Still haven't finished sorting out the web server etc. Never had any real problems with this install method.

    Seemingly a number of initial problems just disappear after a while.

  8. One thing I've noticed on the Apple Discussion site is the number of people using FileVault who either chose upgrade or archive and install and had problems. A few of the people I support reported similar problems. In nearly every case the problem comes when Finder is launching.

    What's happening, I'm certain, is that they've left some third party utility, haxie, or prefpane active that isn't compatible with Tiger. The problem is they can't get to the offending file due to FileVault.

    For this reason, I'm now adding another recommendation to the upgrade process: Turn off FileVault prior to upgrade just to be safe.

    Rob - I didn't want to bring over all my crud either, but I also didn't want to reinstall all my applications. I'm not just a nerdy power user, I'm also supporting a diverse group of people so I have quite a few programs installed that I don't use often but I do own because it allows me to talk users through their problem rather than going onsite. Living in the least populous area of my state, I have clients up to 90 minutes from where I live.

    Anyway...I did an archive and install. Then I removed my library to the desktop and rebooted, creating a new library. Finally, I restored the Application Support folder to the new library as well as a handful of other files. It was, I think, I nice quick solution. My desktop is rock solid.

  9. I have installed Tiger on several machines with no ill effects. I used the Erase and Install option, but I had an available external Firewire drive which was critical to making this a very managable process.

    I first cloned my entire drive to the external drive, verified its integrity, then installed. Ahh, the peace of having a freshly wiped hard drive.

    I then used Tiger's Migration Assistant to bring my Apps and User folders over from the external hard drive. (I know this could introduce instabilities, but it is superior to an Archive and Install in that you do start with a freshly initialized, defragmanted hard drive.)

    I did have to reinstall USB Overdrive, and the Windows Media Player Safari plug-in broke (no big loss). That was solved by manually launching the program before clicking a media link in Safari. Subsequently, it works as expected (not great, but a necessary evil for me).

    Other than those issues, after the Migration Assistant ran, I was up and running. The assistant did add at least an hour to the overall install, but at least it was progress bar time, and not manual file moving.

  10. I also vote for the "fourth" option (clone, clean install, migrate). I'm surprised this isn't mentioned more often (it does require an external drive; however, if you've got a computer without an external backup drive...I pity you ;) ) I got my first taste of the migration assistant when I bought a new powerbook last month- it worked flawlessly. It should also be noted that it appears that Spotlight seems to do its indexing during the migration- Spotlight worked immediately after the migration, and I've never had a blinking Spotlight icon or any attendant system slow down.

  11. I also like the erase and install option as it gives one a clean slate to start with. However, I'd offer a suggestion to use your a clone to allow you to migrate with time. This means a book owner might need to lug around an external for a while but for me it's worth having the ability to jump back into my old setup if something critical doesn't work when I need it. With the creative use of some aliases, and mail settings that keep copies on the server during the transition, one doesn't have to worry too much about keeping track of the latest versions of documents. The clone can also serve as a backup (though ideally not the only one). What's needed is a comprehensive procedure for doing an erase and install (eg what to do with mail, users, etc..) for the common user.

  12. Will doing an Archive and Install with the installer keeping your users, etc. the same cause the same problems as an upgrade? They seem to be identical in result except that you have an archive after the installation with Archive and Install.

  13. asmeurer,

    The difference is that an archive and install installs a completely new system folder, then migrates your user folder, while an update simply patches your existing system to bring it to the new version. If you have problems with your system folder, an archive and install will correct for it, while an update could leave those problems intact. However, if you have problems with your user folder (eg, corrupt preference file), neither will help.

    In fact, even an erase and install will not correct for bad user files if you use the migration assistant after the install. Its main advantage is that it initializes your hard drive, correcting disk level issues and will leave you with a defragmented drive when it is done, the ideal hard drive state.


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