While I remember my stash by color and type, I still have swatch cards with all the info on it: storage location, yardage, width, date purchased, content, price, washing instructions and notes. Everything is filed in an old bank filing cabinet for index cards. Most of my lengths is 3 yards or more.
Most of the time, I go looking for a specific card rather then shopping, my stash.
In all the 20 some odd years I have had a stash, I have forgotten one fabric. Most of the time I can recall my fabric with about a 95% accuracy to the information to the card. I don't forget the fabrics, just forget details like width or exact yardage. Part of it is a good memory and part of it is I don't let it sit and never look at it (I go through the cards at least 3 times a year pretty thoroughly, twice for sewing seasons and once for inventory).