Litestream Writable VFS
Summary
The article explains Litestream's Writable VFS feature for the Litestream project at Fly.io, detailing how a read-write VFS mode enables fast writes during Sprite startup, the buffering strategy, and durability semantics. It also covers hydration, block maps, and how Sprites leverage S3-compatible object storage with local NVMe caches to achieve fast boot and reliable operation, plus how to enable and use these features in practice.