Our Innodb had a corruption, it started small and just kept perpetuating through every backup I had. I keep about a month's worth on hand, every one of them were corrupted. I found two old ones, one had 76 characters of corruption... The oldest had none. I was able to finally get the site back up and running, but we've lost many, many posts, over a year's worth. I don't have to start from scratch, but pretty danged close.