I really want to upgrade to Lion, however I have some concerns with upgrading an OS, believe me, upgrading OS is far too scary for me, anyway, I just read on upgrading from Snow Leopard to Lion, now I want to understand what I have to do, can I just download Lion from the App Store then just open it, which will install Lion.

The part that gets me, when installing/upgrading, will my files on Snow Leopard be intact, because I have so much to transfer if I were to upgrade. I have no external HDD which I'm thinking of buying soon.

All I need is some piece of advice and explanation what goes on in the installation/upgrading process.



Just upgraded to Lion, everything went well! :-)

5 Answers 5


I've had never any problems with upgrades and never lost any files.

You should make a backup — or better, make a bootable clone of your current hard drive:

  • Buy an external hard drive
  • Install Snow Leopard on the external drive.
  • Reboot into the clean external Snow Leopard drive, migrate over users and apps and run all updates. Run from that external to be sure it's a workable copy of your internal drive.
  • Disconnect the external drive and put it on the shelf.
  • Reboot back into your regular internal hard drive and proceed with the upgrade to Lion.
  • Download Lion and run the installer!

Until you're certain that Lion works perfectly, keep the clone around - several months is usually enough time. If you ever need any files from it, just attach the drive and drag-and-drop them. If something goes really horribly wrong, you can boot into the clone, and then clone it back to the internal drive (you'll lose any changes made since you installed Lion). This second drive is really valuable for when you discover three months down the road that one seldom used piece of software won't work on Lion. You can reboot into Snow Leopard where everything still works and get that one task done. It's a great lifesaver and means you can start using Lion rather than checking that every little thing works perfectly right after the upgrade.

EDIT: Thanks Trombone for editing my broken-english post, but please, never add your own ideas into my post. My solution uses pure apple tools, so why bother with SuperDuper, when you can do it with nice clean install and Migration Assistant.

I never recommend any third-party products when things can be done with default Apple SW. Of course, you can prefer SuperDuper, it is your way - but not mine. Please add another answer explaining how to use SuperDuper or other awesome tools so that people can have a choice. Let's keep this solution needing no additional tools.

  • +1'd, but added my own answer to suggest a slightly different workflow.
    – Agos
    Commented Jul 30, 2011 at 20:05
  • Thanks. The upgrade went successfully without a problem! :-)
    – MacMac
    Commented Jul 31, 2011 at 3:35

It is as simple as you just explained. Buy in the app store, wait for it to download, click install, wait for process to complete.

You won't lose any of your personal files.

If you don't have an external drive, I'd also guess you don't have any backups. It is recommended to backup before upgrading. But I've not had any problems or needed them in my 4 upgrades to Lion. Or any other OS X upgrades. (Snow Leopard, Leopard, Tiger, Panther....)

  • 2
    It's not intended to lose any files, but just have a look at the apple discussion boards if you think everyone had a pain free lion experience. :-)
    – bmike
    Commented Jul 29, 2011 at 21:30

No guarantees since the upgrade changes your files forever to work with Lion.

You don't get an undo step or any snapshot, so if things don't work or there is an error, you will have changed your system. A backup is needed if you care to have a second chance - even if it's something silly like a power outage or something drops on the mac from above.

Most (the vast majority) have no issues, so your chances are good and you'll likely have no issues.

But why risk it? A second hard drive is needed anyhow to back up your important files. Only you can know if you can afford to lose work and files - some really don't need anything on a mac as they can create it all anew.


If you really are scared, start with a backup. There is no excuse not to, with external drives getting cheaper every day!

My personal setup and standard procedure, which I heartily recommend:

  • Time machine drive, with time machine backup, updated when I remember to plug it in.
  • On a separated physical drive, a bootable clone of my HD (updated weekly with SuperDuper)
  • Before each 10.x or update (at least): update TM, update bootable clone, unplug the drives, go with update.

Why a time machine backup?

As they say: “There are two kinds of users: those that backup their data and those that will”. Don't wait your first disaster. Don't buy it soon, buy it NOW.

Why a bootable clone?

For a number of reasons:

  1. If my internal HDD failed, my TM backup would be completely useless until I replace it. With a bootable clone, I can continue working roughly were I left while I repair the disaster. Of course YMMV, especially depending on what work you do with your computer.
  2. In case ALL my laptop fails (e.g. logic board failure, screen exploding), I can still work by attaching to some other computer and booting from there.
  3. My TM backup may not be so restorable (see this blog post for an example). TM is really a great technology, but has its points of failures and you really really don't want to experience them.

Why SuperDuper?

Because it can do delta updates, so that I don't have to move half a terabyte every week.
Also, the guy that makes is is super nice. I've never used it, but Carbon Copy Cloner is another software with similar features.

On upgrading to Lion

Snow Leopard improved vastly the upgrade experience (see the Ars review), handling with incredible grace failed installation (I experienced this personally - twice). It is safe to assume that Lion further enhances the process, so (once you have at least a time machine backup), I think you can upgrade with confidence.

Just one tip: the Lion installer has to check your disk and repartition it. This is not really scary (it may be even healthy to your disk!), but this can mean that the “remaining time” could be VERY off; on my laptop, the advertised 33 minutes were more like two hours; resist the temptation (and the panic) and let it finish! Grab a beverage and a good book :)


If you do not have a backup of any sort, you will encounter issues, which may or may not be loss of data. This is Murphy's Law.

Before you spend $30 on the Lion upgrade, get an external USB drive and backup your hard drive using Time Machine, CarbonCopyCloner, or even SuperDuper! You are asking for trouble by not having a backup.

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