Upgrade Apple MAC OS X Lion/Mountain Lion to Yosemite

Hi there,

I don't have much exposure to Apple but if wanted to rebuild an iMAC from Lion or Mountain Lion to Yosetime, what's the best way?  Exclude hardware assuming it's all ok in terms of being able to upgrade.  But in terms of ISO download, upgrade or have to purchase Yosemite?

Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Yosemite is free. Just download it from the App store by pulling down the Apple Menu to App Store. Make sure your hardware supports Yosemite.

Detailed instructions here:  https://support.apple.com/en-ca/HT201475
pjmartinsAuthor Commented:
Thanks Strung,

However that is an upgrade in flight?  Unless that does a wipe as opposed to upgrade?

This is an upgrade in flight. If you want to erase everything, first download and install Yosemite. Then reboot holding down command-r to boot into the recovery partition. Pull down the Utilities menu to Disk Utility and erase the main partition and reformat as Apple Extended Format (Journalled) and then continue to re-install the operating system.
IT Pros Agree: AI and Machine Learning Key

We’d all like to think our company’s data is well protected, but when you ask IT professionals they admit the data probably is not as safe as it could be.

pjmartinsAuthor Commented:
Thanks Strung,

That's the bit i'm unsure, so can i download it as bootable OR do i simply follow upgrade install and then when reboots i can choose where to install?
Mountain lion actually has two partitions on your hard drive. As well as the main partition there is a small  (6 gig, I think) invisible bootable "Recovery Partition" which has some disk utilities on it as well as a system installer.

When you initially download and install Yosemite, it will update the system software on the main partition without erasing and data or apps and will automatically upgrade the installer and utilities on the recovery partition.

When you later reboot while holding down command-r, this will boot you from the recovery partition, which now has a Yosemite installer on it. You can then wipe the main partition and install Yosemite on the main partition while booted from the recovery partition.

This will also wipe all your apps though, except for the basic Mac apps like Mail and Safari. Is that what you really want to do?

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
David AndersTechnician Commented:
The Yosemite download from the App Store is saved into the Applications folder.
When the installer is run, it deletes the download when finished.
If you want to make a bootable copy of the installer, there are guides on MacWorld and utilities that will do this.
How to make a bootable OS X 10.10 Yosemite install drive | Macworld
How to prepare for and upgrade your Mac to OS X Yosemite | MacIssues
I always make a copy of the Installer before I run it.  That way you don't have to keep downloading it over the slow internet.  Just right click or control click on it and select duplicate first.
pjmartinsAuthor Commented:
Thanks all!  One question because this is a small office and we are wiping ALL MACs, how does it with work with Apple accounts, is there one created to manage them all for updates or each user uses their personal?!?
I'm not sure what you mean.  If you've set them up individually, each user can update their own system with their own accounts.  If you've joined them an Open Directory Apple Server, you can control the accounts from the server.

If you're talking about Yosemite, you can just copy it to each system's /Application folder and install it from there.  The Yosemite installer is not tied to the AppleID like other Apps.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Apple OS

From novice to tech pro — start learning today.