Long term source code archiving: Is it possible?

Question

I'm curious about keeping source code around reliably and securely for several years. From my research/experience:

1. Optical media, such as burned DVD-R's lose bits of data over time. After a couple years, I don't get all the files off that I put on them. Read errors, etc.

2. Hard drives are mechanical and subject to failure/obsolescence with expensive data recovery fees, that hardly keep your data private (you send it away to some company).

3. Magnetic tape storage: see #2.

4. Online storage is subject to the whim of some data storage center, the security or lack of security there, and the possibility that the company folds, etc. Plus it's expensive, and you can't guarantee that they aren't peeking in.

I've found over time that I've lost source code to old projects I've done due to these problems. Are there any other solutions?

Summary of answers:
1. Use multiple methods for redundancy.
2. Print out your source code either as text or barcode.
3. RAID arrays are better for local storage.
4. Open sourcing your project will make it last forever.
5. Encryption is the answer to security.
6. Magnetic tape storage is durable.
7. Distributed/guaranteed online storage is cheap and reliable.
8. Use source control to maintain history, and backup the repo.

Answer 1

The best answer is "in multiple places". If I were concerned about keeping my source code for as long as possible I would do:

1) Backup to some optical media on a regular basis, say burn it to DVD once a month and archive it offsite.

2) Back it up to multiple hard drives on my local machines

3) Back it up to Amazon's S3 service. They have guarantees, it's a distributed system so no single points of failure and you can easily encrypt your data so they can't "peek" at it.

With those three steps your chances of losing data are effectively zero. There is no such thing as too many backups for VERY important data.

Answer 2

Based on your level of paranoia, I'd recommend a printer and a safe.

More seriously, a RAID array isn't so expensive anymore, and so long as you continue to use and monitor it, a properly set-up array is virtually guaranteed never to lose data.

Answer 3

Any data you want to keep should be stored in multiple places on multiple formats. While the odds of any one failing may be significant, the odds of all of them failing are pretty small.