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snapzzz3

macrumors newbie
Original poster
I'm sure this has been asked thousands of times but i'm looking to format my iMac hard drive so i want to clear a few things up. Is it absolutely crucial that i backup my hard drive before i format it? Because i don't have an external hard drive to backup to. If i don't backup, will *everything* be gone? Will it delete any essential system files and render my iMac completely broken and useless?
 
Formatting the hard drive will wipe everything on it. *everything will be gone*

Fortunately, the cost of external drives is rather cheap. Best Buy should have ones starting at $50, large enough install an operating system on it (for use as a external boot drive) and to do a time machine backup on it.

I used a USB thumb drive (with a Yosemite upgrade image installed on it) and migrated from a one of those Best Buy drives with a time machine backup on it. Still had some problems getting the user back on my iMac 2007.

Got everything running, but took a bit extra time to get some files permission issues sorted out for my user account.
 
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