Robin Harris enumerates many ways in which you can lose your data. He is not talking only about disks because, disks are just one entity in the story.
This is a world, where complex problems are solved by building systems, where each sub system will do its job and interact with the other subsystem on a whole. The storage sub system is no exception. There are different components that make it up – controllers, disks, software that sits at all layers etc. Each of them can be faulty and can potentially can damage the data that is ultimately stored on the disk.
However, some components are more amenable to failure than others because of their tryst with physics. For example, disks can fail more frequently than controllers and caches as it has a lot of moving parts. Apart from the disk, the software that resides on the controllers and disks can be buggy and can lose data. Robin makes a good coverage of the same.
The point that is driven home is this: You cannot avoid losing all those hardware, but you can avoid losing your data !! – Take backups and save your skin.
I have been thinking about it for quite sometime now (been motivated or concerned after I read a couple of papers from CMU and Google which talks about disk failures). I don’t want to have disk as my back up media again. (I am still not convinced to have disk as the backup media). I am fine with USB drives (i.e. flash drives), CDs/DVDs for the only reason that they don’t have any moving parts and can potentially live longer!. It is my TBD. I will have to start backing up my data – before it is too late.