Disk encryption software
Disk encryption generally refers to wholesale encryption that operates on an entire volume mostly transparently to the user, the system, and applications. This is generally distinguished from file-level encryption that operates by user invocation on a single file or group of files, and which requires the user to decide which specific files should be encrypted. Disk encryption usually includes all aspects of the disk, including directories, so that an adversary cannot determine content, name or size of any file. It is well suited to portable devices such as laptop computers and thumb drives which are particularly susceptible to being lost or stolen. If used properly, someone finding a lost device cannot penetrate actual data, or even know what files might be present.
Packet capture appliance
Some packet capture appliances encrypt the captured data before saving it to disk, while others do not. Considering the breadth of information that travels on a network or internet connection and that at least a portion of it could be considered sensitive, encryption is a good idea for most situations as a measure to keep the captured data secure. Encryption is also a critical element of authentication of data for the purposes of data/network forensics.