I was so thrilled with the idea of a cloud. Finally, my drafts would auto save to every location instantly. The ultimate safeguard. Great in theory. In practice, dangerous.
iCloud autosaved the second draft of my second book, “Daughter of the Earth and Sky.” unfortunately, during the saving process the document was corrupted. To my horror, the corrupted document saved over every viable copy of the draft I had on every computer, iPhone, and other electronic device. My whole book was unopenable.
Fortunately, I’d recently emailed the book to a friend so I was able to retrieve it minus a few of the more recent changes (amazingly awesome changes I can’t even begin to recreate). It’s created a lot of work for me, but it’s much better than it could have been. So word of warning, save multiple copies of your document, email it to friends, and save frequently. Losing a whole book would really suck.
Kaitlin Bevis 
I’m so sorry that happened to you! Good G*d, I’m glad you saved a copy to your friend. I’ve been doing that with my manuscripts as I go, so I’m so glad you posted this to everyone. Yikes. May it never happen again.
C.K. Riffle
Or even just email it to yourself. I know what you mean about the fear of losing an entire ms.! I save it to my hard drive, then immediately save it on a flash drive. I used to save it twice on disc in case one of the discs failed. So I had three backs up, and then I would keep one disc in a safe. I’ve had that kind of situation where something happened that caused me to lose the last draft and I had to go through and redo it.Not fun! SO glad to hear you were able to retrieve a copy. I understand what kind of nightmare that would be to lose it.
Thank you Kaitlin for this warning. My stomach hurts jus thinking about this.