Good day and Merry Christmas to all!

I am looking for opinions on which type of media is best for long-term storage of important business data like emails, tax files, Excel spreadsheets and Word documents, so a time frame of at least 5 years, preferably longer, is required.

Currently we use CD-R or CD-RW, but the amount of data is growing.

I always thought tape was the de-facto standard for long term storage, but lately DVDs seem to get a good rating.

How would external hard drives rate for long-term data integrity assuming the drives had a suitable length warranty?
I assume no warranty will cover the data on the drive though.

Obviously there are significant price differences between the different media and the hardware to drive it, but I am just looking at media reliability at the moment.

Thanks.

For myself personally I just keep the really important files on several computers and I'm looking at running an rsync mirror on a machine at work too.

If I was keeping someone else's (or company) data then I'd probably hedge my bets and go with nightlies on removable HD and weeklies or monthlies on DVD-R using a decent brand of disc burnt at a slow speed.

That said, there are probably as many different methods as there are likely to be responses to this thread!

I tend to think that it doesn't matter what you store it on, it just needs to be in multiple locations, and it needs to be tested regularly, so one bad backup will be caught before the duplicate goes bad. Given those restraints, look at your data, and decide what's best.

I personally rsync to my dreamhost account which gives me 200GB of storage, and keep everything else on external hard drives.

Matthew

I'm curious to know the answer to this, too. I'm wondering how CD-R and DVD-R stack up against things like tape and other magnetic media. How long, for example, would the data on a standard IDE hard disk last if the disk was left in the closet for 20 years? DLT Tape? Etc...

Answer to the CD-R question is here. Still wondering about the others.

That was an interesting read Tony, especially the bit about microwaving CDs!

After some googling I found this on media life expectancy, suggesting that tape may not be the best long-term backup solution compared to optical or hard drives although this appears to be the authors opinion.

Edit: I also found this article that mentions the sources of information for its figures.

I would be interested in peoples experiences with different media in real life.

His opinion on tape is pretty well accepted. It's not really intended for long-term archiving; it's intended for portability and ease of reuse.

Unfortunately, DVD-R (not RW) is probably your best choice. (I've not looked into the aspect of the archive suitability of the various DVD-R dyes. One of the CD-R dyes was chemically unstable and would degrade over time. Make sure the same is not true of the DVD-R ones.) I've had to deal with this in the past and it's not fun. Then again, no aspect of backup and archiving is fun.

Anyway, since DVD-Rs are irretrievably physically changed when burned, they stack up better than magnetic media, which could be affected by passing magnetic fields and which loses its magnetic polarities over time, or RW media, which will lose its data over the passage of time as the thin layer of metal loses its crystallization.

Something recently also highly recommended DVD+R over DVD-R media.

That was going to be my next question:

Should I use DVD+R or DVD-R?

I understood that DVD-R is better for video as it has better compatibility with a wider range of players, and DVD+R is better for data because it has better error correction or something?

[link] How To Choose CD/DVD Archival Media.

I just came across this tidbit from engadget (Posted back in Oct.) about a 100 year lifespan Blu-ray disc. 100GB capacity.

http://www.engadget.com/2006/10/19/panasonic-says-that-its-100gb-blu-ray-discs-will-last-a-century/

But 100 years have not passed yet, which makes me sceptical about manufacturer's lifespan claims.

I read an article a year or two ago about early CDs which HAD been around for many years. Discs which were (is this right?) 15 or 20 years old now were flaking and disintigrating in horrible ways.

Sure, media technology has improved over time, but time itself is the best measure of archive media quality. The previous suggestion of keeping multiple copies in multiple locations is good. I'll suggest archives be "refreshed" by copying their data to new media at reasonable intervals (yearly?). If the data is that important, the cost of media and its storage is negligible.