How to Use This Tool
Turn expected lock duration and live traffic into a visible request-exposure estimate. A migration described as only a few seconds can still queue or fail hundreds of requests on a busy production service.
Why Migration Lock Budget needs more than a raw total
Multiplying live request rate by blocking duration creates an exposure count that teams can compare with their rollback and availability tolerance. For this page, the useful comparison is requests arriving during lock, not whichever input happens to be largest. The Migration Lock Budget result answers the decision in the heading and should not be reused as a score for a different workflow.
The exact Migration Lock Budget formula
Exposed request count equals requests per second multiplied by expected blocking-lock seconds. The visible fields are Application request rate and Expected blocking lock. For Migration Lock Budget, read each printed unit before entry and make the values describe one transaction, cohort or reporting window. If those scopes differ, the displayed requests arriving during lock may be arithmetically valid but operationally meaningless.
Interpreting requests arriving during lock
If the exposure is unacceptable, rehearse on production-scale data and use an online or expand-contract migration strategy before release. The ten-percent comparison is deliberately narrow: it tests the influence of application request rate and is neither a forecast nor a confidence interval. Preserve the values used, their dates and the resulting decision so a later reviewer can reproduce why Migration Lock Budget supported the choice.
What this Migration Lock Budget model leaves out
This is arrival exposure, not predicted failures; it excludes connection pools, retries, timeouts, replicas, transaction scope and database-specific lock behavior. That is where Migration Lock Budget stops being trustworthy. If an excluded factor could reverse requests arriving during lock, extend the model explicitly or use the authoritative account system instead of hiding the factor inside an unexplained adjustment.
Evidence and independent verification
The reference reviewed for Migration Lock Budget is Google SRE Book — Table of contents. Google SRE Book — Table of contents supports the named definition or rule but does not supply private values for requests arriving during lock. Before acting on the result, reconcile the worked example with the relevant dashboard, invoice, export or measurement.
Private, reproducible calculation
Migration Lock Budget runs its arithmetic in the current browser tab and requests no login or API key. That keeps the Migration Lock Budget inputs away from the site's calculation server, while leaving the user responsible for detecting stale data or a changed platform rule. When an assumption changes, reopen Google SRE Book — Table of contents and rerun the saved Migration Lock Budget scenario.
Sources & assumptions
Tool Spec v2 · verified 2026-08-22. Platform rules and fees can change; the editable inputs remain authoritative for your account.
Official references
- Google SRE Book — Table of contents (checked 2026-08-22)
Model assumptions
- Every input covers the same reporting period or cohort.
- This is arrival exposure, not predicted failures; it excludes connection pools, retries, timeouts, replicas, transaction scope and database-specific lock behavior.
- The calculator uses only the visible fields and does not fetch account data.
