Can I reload Mavericks if I don't like Yosemite?

Did you save a copy of the Mavericks installer? If not, perhaps you can still download it from the App Store.

Presumably you have more than one HD in your Mac Pro. The safe way to try the upgrade would be to clone your existing system to a different HD using Carbon Copy Cloner or SuperDuper, and upgrade the clone, leaving your Mavericks system intact. Or just do a clean install of Yosemite on a second drive, and install your critical apps to see how they work with Yosemite..

Once you have installed Yosemite 10.10 on your main boot drive, that drive will not allow you to revert it to an older version.

Techniques to get around this all require a Trusted Backup, because the drive with 10.10 must be set aside or erased before Mavericks 10.9 will install on it.

As kahjot pointed out, if you do not already have Mavericks 10.9 on your Mac App Store "Purchases" page for your main Apple-ID, you will not be able to "buy" it -- it is no longer sold new.

The prudent plan is while you are using Mavericks and if you have the Mavericks GM installer dmg then install Mavericks to an external drive. That way you can boot into it anytime and erase Yosemite then install Mavericks. If you do not do something like I described you'll have a difficult time reverting. I use one external partitioned into 6 with Snow Leopard, Lion, Mt Lion, Mavericks and Yosemite installed along with respective software updaters for any of those OS X.

Takes a little time but worth it in the long run.

Make a bootable clone of you existing Mavericks installation and use that if you do not like Yosemite

http://nyacomputing.com/how-to-create-a-bootable-clone-of-your-mac-hard-drive/

Do not "upgrade" instead do a clean install onto another hard drive.

If you are not using SSD now is the perfect time to buy.

And always keep your existing system as is, clone it regardless, it is your safety net.

And Yosemite will go better this way with clean install.

Setup Assistant can easily import what you need from the old system.

Save those .ESD installer packages, create a bootable installer.

What was on that disk before?

Did you erase/format that disk?

How did you boot to try that?

bluesbo wrote:

Thanks, Illaas. I;ve followed the suggestions on that link, but when I try to restore to another disk, I get the message, "Recovery partition can only be done on GPT partition maps". So what can I do now?