I once did the math to figure out, how much space would be required to track my entire life.
I thought, I would want to know a couple of things: my ___location and my activity for every second of my life. Since I generally live relative to the surface of the Earth, my ___location could be stored in a GPS coord. And since the number of activities I engage in are not that big, I could probably store them as indexes into a map and a 32 bit int would probably give me a sufficient number of unique activities. I doubt I would exhaust that index space no matter how many unique activities I engaged in.
The math is pretty simple from there. Number of seconds in your expected lifetime multiplied by the size of data you want to store per second. Also consider how much of that is compressible (like an ideal 8 hours per day of sleep). Pretty sobering when I think about it.
Assuming a 64 bit number for activities (more than enough, I think!), a 9 character geohash[0], another 64 bits for health (HR, BP, weight, etc.), and you've got 25 bytes per second, 2.2M per day, ~789M per year, and, given 75 years life expectancy (roughly UK average), ~60G per lifetime. Probably just fits on a 64GB USB stick / SD card.
It depends on the amount and type of data you want to store and your strategies for compression. Kind of a good exercise which can be done in 5 minutes in a spreadsheet. Most reasonable answers will easily fit on a modern smartphone (or USB stick, SD card, etc.)
I thought, I would want to know a couple of things: my ___location and my activity for every second of my life. Since I generally live relative to the surface of the Earth, my ___location could be stored in a GPS coord. And since the number of activities I engage in are not that big, I could probably store them as indexes into a map and a 32 bit int would probably give me a sufficient number of unique activities. I doubt I would exhaust that index space no matter how many unique activities I engaged in.
The math is pretty simple from there. Number of seconds in your expected lifetime multiplied by the size of data you want to store per second. Also consider how much of that is compressible (like an ideal 8 hours per day of sleep). Pretty sobering when I think about it.