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Volumes, Bind Mounts and tmpfs: Keeping Data in Containers

A container's writable layer goes away when the container is deleted; data that must persist belongs on a named volume, files from the host on a bind mount and temporary data on tmpfs. With real output we run BookstoreDb on a SQL Server 2025 container with a volume, keep the data across container deletion, back it up with BACKUP DATABASE and tar, fix the non-root SQL Server's Permission denied on a bind mount, use tmpfs for tests and avoid anonymous volumes.