Yes, both latent sector errors (data that is lost that you don't know is lost) and detectable and undetectable bit errors happen at rates high enough to affect

Yes, both latent sector errors (data that is lost that you don't know is lost) and detectable and undetectable bit errors happen at rates high enough to affect 2TB of family photos. NetApp[1] and the Internet Archive[2] have published good data on this in the past. Scrubbing (periodically reading the data and comparing it to checksums) is one way to get around this. It's very effective against small numbers of sector errors in backups (you should have more than one), and in detecting marginal data on drives. It's less effective against some other kinds of corruption. Another option is to store multiple copies (replication), or additional ECC information that can be used to recover the data if one copy is lost. How much effort you put into this really depends on how much you need or want the data. [1] http://www.cs.wisc.edu/adsl/Publications/latent-sigmetrics07.pdf http://www.cs.wisc.edu/adsl/Publications/latent-sigmetrics07... [2] http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.64.1324&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.64....