# Dry Runs A Dry Run is a discovery scan that previews a migration without moving any data. It walks the source and destination, reports file and folder counts and the total size of the data, and surfaces issues like excluded patterns or unsupported filenames. Dry Runs do not count against your [usage pack](/billing.md). Run a Dry Run before every live migration. The results validate that filters work as intended, identify errors that would otherwise stall the migration mid-flight, and give you the data size you need to choose the right [usage pack](/billing.md#usage-packs). Picking a pack without knowing the actual size of the dataset risks hitting a capacity limit partway through the transfer. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://moverdocs.files.com/migrations/dry-runs.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.