Calculating Data Rates and RAID/CFexpress Throughput for ProRes and RAW Workflows
How to calculate sustained write speeds, multi-cam edit bandwidth, and the 3-2-1 backup storage multiplier for production shoots.
Data wranglers and assistant editors must plan for two distinct metrics before production begins: total capacity (TB) across primary and backup drives, and sustained throughput (MB/s) during capture and multi-camera timeline playback.
Sustained Write Speed vs. Sequential Peak Ratings
Memory card packaging prominently advertises peak burst speeds (such as "Up to 1700 MB/s read"), which reflect short cache bursts rather than continuous video recording. When a cinema camera records 4K 60fps Apple ProRes 422 HQ, it writes a relentless stream of 185.2 MB/s (1,482 Mbps) every second until the card fills. If the card thermal-throttles below 185.2 MB/s for more than a few seconds, the camera buffer overflows and recording aborts mid-take.
Planning Multi-Camera NLE Playback Bandwidth
In post-production, a 4-angle multicam sequence shot in 4K 24fps ProRes 422 Standard (\(61.8\text{ MB/s}\) per stream) requires the storage volume to deliver at least \(4 \times 61.8 = 247.2\text{ MB/s}\) plus random seek overhead. A single spinning 7200 RPM hard drive (\(\approx 160\text{ MB/s}\)) cannot play that multicam timeline in real time without dropping frames; you either need an NVMe/SSD working drive, a multi-disk RAID array, or a batch of ProRes 422 Proxy files (\(19\text{ MB/s}\) per stream, or \(76\text{ MB/s}\) total for 4 angles).