No rational person would bid above the on demand price, so the spot price will never rise above the on demand price. Therefore if I bid just above the on demand price I'll never be outbid, and I won't have to deal with automating the switch from spot to on demand instances.
Funny you should mention that. There was a blog post I had read where they were discussing an unfortunate AWS customer who bid $999.00/hour for Spot instances thinking it would protect their running servers from shutting down. Little did this person realize, Amazon - unlike eBay - doesn't just accept the next highest bid, they accept THE highest bid. They were running a Spot instance for an entire month at $999/hour. Ouch.
That's not true - the price you set is the max price you're willing to pay. If your price is higher than the current spot price, you pay the current spot price. The blog post author must be mistaken somehow.
What do you suppose is displayed when there are no spot instances available, because all resources are being used for on demand instances or there's some problem with the spot market system?
No rational person would bid above the on demand price, so the spot price will never rise above the on demand price. Therefore if I bid just above the on demand price I'll never be outbid, and I won't have to deal with automating the switch from spot to on demand instances.
Needless to say, this logic is wrong.