Upgrade or reformat?

[Julius Caesar]

Is there any advantage to performing a clean install of Lion versus upgrading from SL? Windows users recommend performing a clean install instead of upgrading a previous version of the OS. Does this advice apply to OS X?

[baryon]

In Windows, things like the Registry get cluttered and carried over from OS to OS. On Macs there is no such thing, but instead you have folders in User/Library/Application Data that contain all kinds of remains of old apps. You may want to manually delete all the ones that were created by apps you no longer have instead of doing a clean install.

When upgrading your Mac OS, your entire system folder will get replaced by the new system, so there should be no problems with the system itself. The only think you may want to look into are the various preference files, corrupt fonts and cache files that your computer has accumulated over time, that you might want to get rid of.

If you do a clean install, make sure you don't migrate your data back from Time Machine, as this defeats the purpose of a clean install: Your Application Data will get restored, just as if you didn't do a clean install.

I think that the smartest thing to do is to simply do an upgrade, see if you're happy with it, and if not you can easily do a clean install from the recovery partition.

[AndyK]

I'm completely reformatting and wiping all my timemachine back ups as well, with simply my personal files backed up manually. It's been so long and I have so many back ups I really want a fresh start with the new OS.

I can finally loose all the rubbish I really don't need any more!

[craig1410]

Originally Posted by AndyK

I'm completely reformatting and wiping all my timemachine back ups as well, with simply my personal files backed up manually. It's been so long and I have so many back ups I really want a fresh start with the new OS.

I can finally loose all the rubbish I really don't need any more!

I'd urge some caution there. The one time when you might need to rely on your backups is right after you've done a system-wide upgrade! This is the first release of Lion so there will be bugs, perhaps serious ones which cause data loss. My advice would be to buy an external drive big enough to back up your entire system drive and use Carbon Copy Cloner or SuperDuper to create a clone of the system drive before you upgrade to Lion. Then worst case, if Lion has issues which you can't live with, you can boot from that cloned drive and use it as if nothing has happened until the issues with Lion are resolved.

I understand your wish to clean out your Time Machine drive, mine is getting pretty full too and I will most likely do the same thing as you but I'll be taking a clone as described above and then unplugging my Time Machine drive for a few days to ensure everything is running fine. Then I'll reformat the Time Machine drive and do my initial backup and leave it running thereafter. The cloned drive will be left for at least 3 months before I even think about reusing it and in all likelihood I'll leave it for longer than that.

Cheers,
Craig.