Upgrading from Snow Leopard to Maverick

What danger is there in upgrading my system software without backing up EVERYTHING first? I do not have a separate hard drive to use, and do not have enough space on my thumb drives (got plenty of old Zip Disks though!). I realize the importance of having a back-up, and will certainly back-up my working files and photos, but is it really necessary to back up everything else?

I've done this several times with different versions of OS X without any real issues. It's not what I would call the best practice but can be done usually without incident. Here are a few things to keep in mind though:

1. Always, at a minimum, have a backup of any mission critical data. Things can, and sometimes do, go wrong.
2. If you are still running Power PC versions of some software you won't have access to that software without upgrading it. Snow Leopard was the last OS that ran PPC software.
3. Although you can upgrade without doing a backup I strongly suggest cloning your Snow Leopard installation. The response to Mavericks has been good but we do get posts regularly wondering how to revery to Snow Leopard. This is much easier to do with a working SL clone.

I've also done a lot of Mac OS upgrades without backing up first. But this is because I didn't have anything on the computer that if lost was any big deal.

Usually if there are apps I have installed…I have original media to reinstall them (or redownload from the Mac App Store or iTunes). And if I have any important files, videos, documents, etc….I back them up on an external HD or thumb drive.

Rarely does an Mac OS upgrade "go bad" (Apple makes it easy…and usually bullet-proof)…but things can happen.

- Nick

Always have a backup, upgrading or not.

Older PowerPC application such as Office 2004, which are PowerPC, will not work on Mavericks. Also computer details would help a lot with memory suggestions. Vital information.