However, I'd probably go for single-sided single-layer DVD+R, which has better error checking and synchronisation than the earlier DVD-R system. Unfortunately, there are several different types of disc (single/double-sided, single/dual layer etc), and many different ways to write the data. If I still made movies, I would do backups on DVDs, which can store up to 4.7GB of data. I do have some music files, but at home I still play the original audio CDs. In my case, it's photos (typically up to 4MB each) and articles (10K to 100K), plus a small number of original recordings in MP3 format (30MB to 100MB). Partly, it depends what you want to back up.

I am thinking of switching to SD cards, which can now hold lots of data – 32GB is affordable – and take up very little space. That was fine when I started, but it is becoming less viable every year. Their main limitation is that a CD will only store about 700MB of data. All my backups are on write-once CD-R discs, which I reckon is the best bet for data you want to last 10 or more years. The long-term reliability of optical discs is still unknown, so there are no certain answers. I am fairly sure everything is copied somewhere separate at least once, but we need a better system, possibly involving a network server.

We have an external USB hard drive on the main desktop PC as the primary backup, plus an assortment of thumb drives and also, in my case, a laptop. We are contemplating a new computer, which has drawn attention to the rather muddled state of our folders and backups, especially of photos. I have used these for DVD recording and they seem to work well without any initialisation or finishing faff. I have just been re-reading your article on Backing up digital photos, and would like your opinion of using DVD-RAM discs for this purpose.

Why are cd-r more expensive than dvd-r