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The size of your instance’s disk directly affects how long snapshots take to create and restore. This guide focuses on simple, high-impact steps to reduce snapshot size and speed up restores. We’ll expand this guide as more snapshot features ship.

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Quick Wins

  1. Keep your instance disk lean: Remove large, transient files before snapshotting.
  2. Exclude non-essential data: Use .thunderignore to skip caches, build outputs, and generated assets.

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.thunderignore Files for Exclusion

Often, you may want to exclude certain heavy files, cache directories, or generated files from a snapshot. You can do this using a .thunderignore file. This will help speed up snapshot creation and restoration.
  1. Create a .thunderignore file in the / directory of your instance.
  2. Add all paths you would like to ignore (absolute paths or relative to /). Patterns are supported - the syntax for these is the same as filepath.Match in Go. Patterns are matched against paths, not just basenames, so use / to anchor from the root (for example, /data/*.parquet). * and ? are supported; ** is not special and is treated literally. Blank lines are ignored, and lines starting with # are treated as comments.
  3. Create your snapshot. The .thunderignore file is included in the snapshot so your exclusions persist on restore.
Start by excluding caches, build outputs, and temporary files. You’ll usually see the biggest size reductions there.
Make sure you don’t exclude anything required to run your workloads after restore, such as model weights or datasets you actually need.
Example .thunderignore: 
# Caches and build artifacts
.cache/*
*.tmp

# Large data
/data/*.parquet
/models/*.pt

# Common language build outputs
/node_modules/*
/dist/*
/target/*