Replication Backlog Catch-Up Calculator

Method, formula and assumptions

Net drain = replay rate - new change rate. Catch-up seconds = backlog / net drain. Remaining backlog is max(0, backlog - net drain x window seconds).

Input definitions and supported units

• Current backlog (MB): Measured or assumed numerical value, from 0 to 1000000000; zero is supported where the stated method permits it.
• New change rate (MB/s): Measured or assumed numerical value, from 0 to 1000000; zero is supported where the stated method permits it.
• Sustained replay rate (MB/s): Measured or assumed numerical value, from 0.001 to 1000000; must be positive.
• Catch-up window (minutes): Measured or assumed numerical value, from 0 to 1000000; zero is supported where the stated method permits it.

Worked example with answer

A 6,000 MB backlog with 20 MB/s arriving and 30 MB/s replayed drains at 10 MB/s and catches up in 10 minutes. A 15-minute window leaves 0 MB and 5 minutes margin.

How to use the results

This differs from a static transfer: the source keeps producing work. Equal or slower replay is rejected explicitly rather than returning an impossible finite catch-up time.

Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.

Limitations and references

Assumes stable rates and no additional stalls. Use measured payload/replay rates in the same units; it is not a PostgreSQL or vendor tuning recommendation.

The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.

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