Copy-window planning

Media Offload Time Planner

Estimate how card readers, destination speed, parallel copies, and verification change the time between wrap and safe handoff.

Decision guide

Reserve enough time for copies and evidence

What this tool helps you decide

This planner estimates whether a specified camera-card batch can reach one or more destinations and complete the chosen verification process inside the real offload window. It exposes the active reader count, aggregate source rate, destination limit, card waves, copy duration, and verification duration. Use it to decide how many readers to carry, whether the destination path is fast enough, and when a full re-read makes the schedule exceed call time.

Before you start

Measure a representative full-card transfer through the exact reader, cable, hub, computer port, application, and destination type. Record sustained MB/s rather than a brief peak or interface label. Estimate only primary source data; two destinations written simultaneously each receive those bytes, but the card is not read twice in this model. Choose the verification behavior used in practice and measure destination re-read speed when that option applies.

How the calculation works

Active readers are the smaller of available readers and cards. Their count multiplied by measured per-reader speed forms the aggregate source ceiling. The copy rate is the smaller of aggregate source speed and per-destination write speed, reduced by workflow efficiency. Copy time divides decimal gigabytes by that effective MB/s. Inline hashing adds a modest planning overhead, while full re-read verification conservatively reads each destination's payload in sequence at the slower of verification and destination speed.

How to interpret the results

The modeled bottleneck identifies the first component worth testing, not an automatic purchase instruction. If readers limit the path, another reader can help only when ports, hubs, CPU, and destinations accept the added traffic. If the destination limits the path, more readers create no modeled improvement. Card waves describe handling rounds; even a fast aggregate path may need operator time between waves. Compare the total with the usable overnight or meal-break window, not merely elapsed wall-clock time until the next shoot.

Worked example

Consider 420 GB across eight cards, two 180 MB/s readers, 500 MB/s destination writes, and 80% efficiency. Two active readers provide a 360 MB/s source ceiling, so the modeled copy rate is 288 MB/s and copying takes about 24 minutes. With two destinations and a conservative full re-read at 450 MB/s before efficiency, verification adds roughly 39 minutes. The total is about 63 minutes across four reader waves.

Assumptions and limitations

The parallel-destination model assumes software can read a source once and stream to every destination together. Applications that copy sequentially require separate runs. Small files, thermal throttling, bus sharing, encryption, checksum CPU use, power policy, cable problems, file-system metadata, nearly full SSDs, and operator swaps can lower throughput. The inline percentage is a planning allowance rather than a benchmark. Successful elapsed time does not establish integrity unless the selected process produces and reviews evidence.

Next steps

Run one dress rehearsal and replace every nominal speed with the observed sustained result. Preserve the tool output with application settings and verification reports. Use the total duration in the Memory Card Rotation Planner to see how long source cards remain unavailable. If portable destinations might fill during the trip, allocate them with the Field Backup Drive Planner before changing readers or hubs.