iMac won't boot off of Mavericks USB when downgrading from Yosemite
Solution 1:
The Booting from USB issue
Ok, so first off. I don't know how you made the bootable USB, but for the sake of consistency in my answer I will give you a method to use:
- Download Mavericks for the App store. (I checked, it is still there for downloading)
- Plug in the USB drive you want to boot from (has to be 8GB or more)
-
Then from the Terminal app run this command:
sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Mavericks.app
It takes a while to complete so go make yourself some coffee and let Mac OS do it's thing.
NB Notes:
- Replace
MyVolumewith the name of your USB drive. - If you have already downloaded Mavericks and backed it up somewhere, you can just copy it back into the Applications folder. It has to be called
Install OS X Mavericks.app.
Taken from Creating a bootable OS X installer in OS X Mavericks.
If you boot your Mac, immediately hold down the ALT key and select the USB as the boot device. This should boot into the Mavericks installer. From there you can run DiskUtilities and partition you OS hard disk and install Mavericks.
The NTFS issue
It sounds like you might have had a 3rd party app like Paragon installed. Mac does not natively allow writing to NTFS.
Solution 2:
You need to make sure that you are using the correct build for your iMac.
In this document: http://support.apple.com/kb/ht1159 you can find the exact build for your iMac, then you have to make sure that you are using a 10.9 version after the minimum build your computer requires. In case you have trouble with that, I find that the best way is to "buy" mavericks from a similar computer and then create the install disk using Disk Maker: http://liondiskmaker.com/
After that the computer will reboot from this installation disk and you will be able to install 10.9, but you cannot transfer information from your old hard drive, since migration assistant cannot migrate from an older version, so you will need to do the migration manually, which basically is copying folders from your old drive or backup, to your new drive.
Please let me know if you have any doubts I did not want to extend myself much and take for granted that you are familiar with many of the procedures.