There is a finite lifespan for today's media and it varies from manufacturer to manufacturer. For dvd's there is no real standard, currently, for measuring lifespan across all manufacturers. So we'll look at the average. For dvd-r or dvd+r media its between 30 yrs and 100 yrs. with the 100 yrs probably being an outside, wildly optimistic number. One decent scratch on it and its data is damaged, probably lost forever to your posterity. A USB flash drive or a micro sd card are both good to consider. They are both electronic storage mediums with non volatile memory, meaning that a power source is not required for them to hold your data in memory. They are more durable than dvd media. A usb flash drive is larger than a micro sd card and therefore more durable, less likely to get lost. USB flash drives are capable of handling 10 thousand to 10 million write and erase operations during their lifetime, depending on the source as well as the specific USB drive. Regardless, a flash drive typically will outlast any standard hard drive. The main concerns about the life expectancy of a flash drive are damage from neglect and becoming lost or stolen. Insuring that future generations will be able to use the device you choose is another matter. The suggestion posted about including the equipment to read your media is a good one on the surface, but also consider that the more equipment you choose to store in your "attic" time capsule, the more probability it will become damaged or degraded over time. Unless there is some great technological disaster in the future, they will be able to read a USB drive in 100 or 150 yrs. If a disaster does happen, then storing photo's is your best bet. It worked for your family album for more than 150 yrs. Whatever you choose, keep it stored in an air/humidity free environment.
I am currently preserving very old family photos and film etc: and a very good question came up and that is What is the best storage device to use that we can attach to an old photo album etc:
The reason we ask is that we found some very old documents hidden behind a family photo from 1865 when they made the trek from Georgia-Louisiana to Texas.
We thought what a good idea it would be to store our current history behind the photo to be passed down the generations but do it in the form of our current history and that is the form of a small usb device etc: But our question still remains....What is the best small device we can use for long-term storage or can an E - device even be used to store photos etc to last Generations?