Data Encryption Can Drag Down NAS Performance
"Three vendors of network-attached storage, Qnap, Synology, and Thecus, sent over Intel Atom-based NAS servers to test the effects of protecting your data via encryption. But performance and configuration options are not identical, as our testing shows. Once you start getting into higher-end networked storage devices for SMBs, you often see value-added features like the ability to encrypt stored data to improve security. There are different ways to achieve this, which depend on the vendor. Some employ encryption at the partition level, while others encrypt at the file level."
If you've got a high-end NAS device - typically deployed in business scenarios - you may want to think twice about enabling data encryption. Depending on what type of hardware your NAS uses, and how encryption has been implemented, performance could fall off a cliff. Read up!