How does the Perseverance Rover store/process large quanties of images?

Question

Dave Gruel (EDL Cam Sute Lead) mentioned on the surface update press conference (22 Feb) that that they collected 30GB of information, including 23,000 images. Where did this information go?

Wikipedia (referencing a JPL paper) tells me the rover has 4GB of flash (a NASA educational page says 2).

To get a rough sense, 23,000 images would equate to 12 minutes of video at 30 frames/sec, though there are multiple cameras at varying frame rates. Its too much information to be streamed to an orbiter via the 2Mbps UHF link to orbiter. They could be compressed (JPEG is typically 10:1), or downsampled (in resolution or color depth), but I would have thought that would have limited their scientific value. Does the computer make decisions to keep/discard images on the fly? (or otherwise keep a mainly downscaled images with a few high-res frames)

Answer 1

From the open access article The Mars 2020 Engineering Cameras and Microphone on the Perseverance Rover: A Next-Generation Imaging System for Mars Exploration, emphasis at the end mine,

Data Storage Unit (DSU)
In addition to six cameras and a microphone, the EDLCAM system includes two data storage units (DSUs) and two USB3 hubs. The DSU is an off-the-shelf computer-on-module (CoM) from CompuLab Ltd with an Intel Atom processor and solid-state memory. The DSU runs the Linux operating system, along with additional software to communicate with the EDLCAM sensors, perform the EDL data collection sequence, manage the data storage and compress the collected data files. The DSU uses a high-density connector to provide connectivity to the high-speed USB3, USB2, gigabit ethernet and SATA interfaces.

The main DSU is located inside the rover body. A second DSU, the descent stage DSU, is located on the descent stage. In both DSUs the CoM is connected to a custom electronics board that provides connectivity for all the USB devices. The two DSUs are almost identical to each other and communicate with each other through a gigabit ethernet link. The rover DSU includes a 480 GB solid-state flash memory drive (SSD) for data storage, provides a gigabit Ethernet link between both DSUs, and implements the high-speed serial communication protocol to communicate to the rover computer.