I just downloaded Lion and am pretty eager to install it, but I can use every minute I have, so I'd rather not install it now if it means my system is unusable for 30+ minutes.
How long should I expect a Mac to be unusable during the upgrade process?
Best Answer
It's a safe bet that most people are out of business for less than an hour. Of course, you'll probably be spending hours exploring all the new features, so you might want to count that against your system being unusable for "real work" due to "exploration and play".
Since you can't easily interrupt things and won't have use of the mac once the installer logs you out to start the upgrade, do give yourself a little window in case things run long.
Here are some ballpark numbers people are reporting for upgrades with real life amounts of data on their macs:
Furthermore, you won't really know how long it will take if problems crop up moving thousands of tiny files or the process hangs. Then you will need to research what to do if trying again doesn't sort things out for you.
Even if your install should take 15 minutes, why risk it until the pressure is off?
The problem with any prediction is that there are four parts to the install:
Parts 2 and 4 are where "slow installs" take the majority of your time.
Most people will be done in less than an hour - but you can't really know if your install will go long until you let it start. It matters little that other people had a good experience if your is going to be especially slow.
You can run a full file system check before starting to be sure your directories won't trap the installer in an infinite loop, but other than deleting things like un-needed apps and files that might need "migration", you can't speed up the parts of the process that depend on your pre-existing data.