The low-level storage API provides a set of commands to asynchronously read, write,
and flush hardware caches at any offset and of arbitrary size in a VSA via a command
queue in the associated VSIC. To do so, the caller provides an array of virtual
memory ranges (address and size) in RAM to be read/written, the VSA identifier, the
queue number, and the matching array of ranges (offset and size) within the VSA.
The implementation enqueues the corresponding commands to the VSIC, coalescing
and reordering commands if this makes sense to the underlying media. I/O completion
events are reported using doorbells. On top of this, a POSIX-compliant file system is
provided.