A storage system, comprising: a first storage system and a second storage system connected to a network; the first storage system includes a first central processing unit, a first memory, and a first storage device coupled to the first central processing unit and first memory, the first central processing unit is configured to manage a first namespace which contains data and metadata associated with the data, the data and associated metadata are stored in the first storage device; the second storage system includes a second central processing unit, a second memory, and a second storage device coupled to the second memory and the second processing unit, the second central processing unit is configured to manage the first namespace which contains data and metadata associated with the data, the data and associated metadata are stored in the second storage device, wherein the first storage system is configured to receive a write request of first data, the first storage system is configured to store the first data and first metadata associated with the first data in the first storage device within the first namespace managed by the first central processing unit, the first storage system is configured to transfer the first metadata to the second storage system, the second storage system is configured to receive the first metadata transferred from the first storage system and store the first metadata into the second storage device within the first namespace managed by the second central processing unit, and the second storage system is configured to make the first data accessible to a client of the second storage system irrespective of whether the first data associated with the first metadata has been transferred to the second storage system. a first storage system and a second storage system connected to a network; the first storage system includes a first central processing unit, a first memory, and a first storage device coupled to the first central processing unit and first memory, the first central processing unit is configured to manage a first namespace which contains data and metadata associated with the data, the data and associated metadata are stored in the first storage device; the second storage system includes a second central processing unit, a second memory, and a second storage device coupled to the second memory and the second processing unit, the second central processing unit is configured to manage the first namespace which contains data and metadata associated with the data, the data and associated metadata are stored in the second storage device, wherein the first storage system is configured to receive a write request of first data, the first storage system is configured to store the first data and first metadata associated with the first data in the first storage device within the first namespace managed by the first central processing unit, the first storage system is configured to transfer the first metadata to the second storage system, the second storage system is configured to receive the first metadata transferred from the first storage system and store the first metadata into the second storage device within the first namespace managed by the second central processing unit, and the second storage system is configured to make the first data accessible to a client of the second storage system irrespective of whether the first data associated with the first metadata has been transferred to the second storage system.