Encrypting data at rest for HPC systems is almost always desirable. But doing so in an open Lustre system involves cost and performance trade-offs. Software encryption imposes performance penalties undesirable in HPC systems, whereas hardware systems traditionally required vendor-locked and expensive proprietary approaches. This talk will discuss how WARP Mechanics architected a simple software solution for managing COTS hardware self-encrypting HDDs, to strike a balance using high performance hardware encryption with low cost open software.