I have come to the realization from personal experience that while everyone agrees on the necessity of performing regular backups, SMBs tend to skip a crucial step in their disaster recovery strategy - actually testing their data backups to ensure that they are usable.
Testing backups in order to confirm their recoverability might sound like a lot of work - and it is. Yet it is the only conclusive way of ensuring that all necessary data is duplicated. Indeed, it will not be unusual for flaws in disaster recovery to be revealed during the testing process.
I was browsing through the Internet recently when I came across an older article on TechCrunch narrating how a popular Web destination had no choice but to close down in the wake of multiple simultaneous database glitches.
In what could only be billed as an obituary, creator Casey Fenton wrote a final e-mail that was sent out to the 90,000-member user base. Fenton called the case a "perfect storm" in which an avoidable hard disk failure took down several crucial data files vital to the operation of the site. Human error by two database administrators meant that these files were not picked up by the scheduled backup regime. Ironically, the fatal error occurred as the company was in the midst of transitioning to a different back-up method - which I'll imagine to be a better one.
While all this transgressed in 2006, it bears an important lesson, especially small and medium-sized businesses that simply do not have access to the services of specialized vendors or independent consultants.
In the past, the only way to test the completeness of data backups would be to purchase a separate set of hardware to replicate an organization's operational environment. With virtualization, though, it is possible to do the same on a very small subset of servers. Moreover, these servers can be utilized for other uses post-test.
I know of at least one enterprise that holds regular disaster recovery exercises in order to evaluate both backup hardware and software components. There is no reason smaller companies cannot do the same thing. Testing of backups should not be optional, and the failure to do so could result in crucial data being irretrievably lost.