The invention provides a key-value storage device, a host and a host storage system. A host in communication with a key-value storage device includes: a host memory storing a computer program; and a host controller including a processor configured to run a computer program. The computer program is configured, when executed, to cause the processor to process a file or directory related to file data received by an application stored in the host, and to provide the file or directory to the key-value storage device, map the file or directory to a key-value object that can be stored in the key-value storage device, in one embodiment, a method includes storing a key-value object, converting a file operation requested by an application stored in a host into a key-value operation executable in a key-value storage device, managing transactions related to the key-value object and the key-value operation, and providing the transactions to the key-value storage device, and abstracting a file or directory into a meta-object or a data object.
