When you try to play your recording in two years' time, what will you hear? Nothing?
You put a lot of hard work into your music and your recordings, right? You expect to be able to play your recordings at any time in the future. But the reality may be that your recordings might become unplayable in as short a time as just a couple of years, or even less.
Comments on this thread make the situation clear. So let's consider the options for safe storage.
Analog tape - Analog tape is a known quantity because it has been around so long. Recordings made as long as fifty years ago are still playable. Not all of them, granted, but there is a great fund of experience available now that means that the tape you record today should still play in 2055 or later. But you might need to learn tape baking techniques to ensure playability.
Digital tape - Digital tape such as DAT has only been with us for a couple of decades so real-life data on digital tape longevity isn't available beyond that. However, my personal experience with DAT is that I haven't had a single tape fail due to age. I recently checked out some tapes I recorded in 1987, and they still play fine. Reports of your experiences are welcome.
Hard disk - No way, no way, no way! Hard disk is not a safe storage medium. Hard disks are liable to fail spontaneously without warning. There are data recovery services available, but at tremendous cost, with little certainty of success with the large and many files involved in audio production.
Data CD-R - Not in my experience. I recently pulled out a CD-ROM I had burned only two years ago. Guess what - totally unreadable. The disk looks totally clean, and I tried it on three drives with no luck. Fortunately I had made two copies... but the other copy didn't work either!
Data DVD-R - DVD-ROM ought to be more secure than CD-ROM. The reason for this is that where the data layer is very close to the label surface of a CD, a DVD is made of two protective plastic layers with the data layer sandwiched in between. But in my experience, DVD-ROM can't be fully relied upon. Mostly they work, but sometimes they don't.
We're not doing very well, are we? But there is hope...
One of the problems with all forms of data disk format is that when they fail, they often tend to fail catastrophically. You lose the whole lot. Compare that with tape, analog or digital, where if there is a problem, it is localized and you have only lost a part of your work. A problem, yes, but not as bad as losing it all. But there are disk formats where you don't necessarily lose everything...
Audio CD-R - Audio CD-R is a surprisingly resilient format. Although the disks are the same as Data CD-R (the writable equivalent of a CD-ROM), they are not totally reliant on their table-of-contents data to work successfully. So an Audio CD-R can be scratched or damaged in places, but the rest will still play. In fact, if the scratches are on the data side, then they can often be polished out with complete success.
DVD-R - Now this is probably the ultimate in safe storage of any of the formats you can record in the studio. If you record audio to a DVD in the DVD-Audio format, then not only do you have the opportunity of excellent sound quality, you have a disk that will play even if partially scratched, or fingerprinted. And a DVD is robust on both sides, not just on one side like a CD. But you'll need a DVD-Audio player to play the disk on.
If you really do want the ultimate in safe storage, then in the studio you can make Data CD-R's and DVD-R's, and also Audio CD-R's and DVD-R's too - preferably on different brands of media to spread the risk.
However there is probably no more sure way of storage than getting a CD or DVD manufactured by pressing rather than recording. Apart from rare cases of 'CD rot', which seem to be traceable to certain pressing plants, both CD's and DVD's are extremely robust. And if you can sell a few thousand copies, then you will always be able to find a good copy on eBay, should your own copy get lost or damaged.
I'm sure these are not the only ideas on safe storage. You want your music to stand the test of time - what do you do to ensure safe storage?