Let's suppose that a malicious hacker does manage to gain access to your storage. What now?

In the absence of airtight security, your best bet may be to encrypt your data where it resides, says Phil Grasso, vice president of marketing at Vormetric.

Encrypting data at rest, so to speak, isn't a new idea, but most existing encryption products don't take into consideration the concerns of storage managers, notably, performance and transparency, advocates of the technology say.

For performance reasons, Vormetric and its competitor NeoScale each take an appliance approach, and claim to encrypt data at wire speed.

Addressing storage transparency is trickier. By encrypting data, "you want to make sure encryption doesn't break, say, virtualization," Grasso says.

Ultimately, encrypting data is "the last line of defense because we are protecting the core data," says Scott Gordon, vice president of marketing at NeoScale."No one product is a silver bullet."