Originally posted by ThorSanchez I've never had a failed SD card disaster, but just the thought of losing most of a vacation's worth of photos has me learning to program bash scripts in linux to turn a Raspberry Pi into an auto-backup device, on top of the two cards in my K-3ii. And on past big vacations I've always taken an external hard drive and backed everything up frequently.
I've had one situation where, after a day's shooting, several raw photos - a block of three or four (in sequence, if I remember coorectly) were corrupted on one card, but fine on the other. This was with my Hasselblad HV, not a Pentax camera. Obviously it wasn't an issue, as I was able to get images from the second card. I never was able to find a fault with the card in question... I reformatted it and ran read / write tests, but no errors were returned. So, it could have been an intermittent fault with the card... or it could even have been an intermittent hardware or firmware fault with the camera. I retired the card, and it's never happened since.
Come to think of it, I seem to recall having a total card failure in a compact camera some years back. Long time ago, though... maybe ten years?
I own some cameras with only a single card slot, and I'm more than happy to shoot with them given that this really is just a hobby for me. If I lose some photos, I'd be disappointed - but that's all. If I was a professional photographer, I'd absolutely insist on two card slots. As it is, if I have the choice between one or two slots, I'll take two every time, just for peace of mind.