My Photo collection is about 400 GB and have over 15,000 images. I have what I think is a great backup system. My system is Files live on a iMac and are backed up weekly (or with major changes) to a mac mini server running crash plan, the mini server is also backed up locally daily. I also have a off site backup at my work and a disk I carry around with me in my bag. All backup are refreshed every week. So I think I am covered. However I have been reading about data rot on hard drives and it got me thinking, some of my images I may not open let alone re-save for years. How can I protect my collection from data rot. The backup are made with either super duper or rsync. And OS X has not built in data checking so if a file has gone bad the bad copy just migrates through the backups. Or is Data rot something that is so rare that it is not worth worrying about.