Is it risky to upgrade snow leopard without a backup.

It's risky not to have a backup at all.

 

Well, from my point of view, you need a backup either way. You should at least have a drive dedicated to Time Machine.

I don't think there's anything particularly risky about upgrading to SL, though. For the vast majority, it'll go without a hitch.

 

If you don't have a backup, then don't buy Snow Leopard, take the money and use it for an external hard drive so you have a backup. Seriously, if you don't have a backup than that external drive is ten times more important than Snow Leopard.

 

If you have no backup, you should be buying an external HD or something to make a backup before you think of Snow Leopard or Polar Leopard, or anything else.

 

i don't have a backup, and i upgraded both of my computers to SL.

 

My guess is that you can install SL without a backup. I had no problems installing it on my two uMBPs.

However, I would strongly recommend you do get an external hard drive--not because SL will destroy your data. I have had hard drives fail in the past and my back-ups saved my life.

 

If you have nothing to lose (i.e. no value placed on your mac's data) then there is no risk. It's as simple as that.

At the very least you can always get a pack of blank DVD's and a backup a few things.