Drives

Drives (slice D8): disks of a project's that outlive the sandboxes that have them, each a block device with its own ext4, copied into the object store as it is written, and mounted read-write by one sandbox at a time, on any node of its region. A Drive is a volume of the kind drive: /v1/volumes shows it too, as it did. A snapshot of a Drive (slice D7) is a version of it in the object store, nothing copied: taken (POST /v1/drives/{id}/snapshots), forked into a new Drive, restored to, and mounted read-only by any number of sandboxes at once (mode snapshot); it outlives its Drive, and is billed for what it keeps alone.