> how do you even know that the cloud company will even exist in the next 25 years You don't and trying to guess which technology or provider will still exist

> how do you even know that the cloud company will even exist in the next 25 years You don't and trying to guess which technology or provider will still exist in 25 years is probably pointless. If you want to keep your data for extended periods of time (decades) the best strategy is to a) define what you want to protect against and don't go for "everything" or it will be prohibitively expensive and impractical, b) have at least one redundancy (an ECC file, a full copy, whatever helps you recover the data if one data set is affected), and c) ensure that the data sets cannot fail at the same time, statistically speaking, by using completely different methods. A CD will fail suddenly because you probably can't check it often enough. A major cloud provider doesn't disappear over night though. Keep the parity file in two completely unrelated clouds maybe even for free, or keep the whole data in highly compressed archives with recovery record in multiple clouds for a cost. Keep a full copy of your data on different HDDs with (different?) resilient file systems, and connect them periodically for a sanity check. Check periodically that you can still use the data, having an intact file isn't enough if you can no longer open that format used in 1993. There is no one size fits all and the is no set and forget "this backup will be guaranteed for the lifetime of the universe" answer. Choose what you protect against and choose how much you're willing to pay in time, effort, money. Then play whack-a-mole as some of your backups are no longer viable and you replace them to always have that +1 minimum resilience.