a physical storage device controller (PSD controller) (81) for receiving a first control signal from the first storage virtualization controller (SVC 1) (10) to confirm that the first storage virtualization controller (SVC 1) (10) is a primary controller of the physical storage device (PSD) (9), and generating a first selection signal, wherein when the physical storage device controller (PSD controller) (81) detects the physical storage device (PSD) (9) that is coupled, the physical storage device controller (PSD controller) (81) sends a notification signal to the first storage virtualization controller (SVC 1) (10) which acts as the primary controller to inform the first storage virtualization controller (SVC 1) (10) of availability of the physical storage device (PSD) (9);

a selector (83) for receiving the first selection signal to select data and signals from the first storage virtualization controller (SVC 1) (10) according to the first selection signal; and

a clock generation circuit (85) for providing a dedicated clock signal to the physical storage device (PSD) (9);

wherein when the physical storage device controller (PSD controller) (81) receives a reset signal from the second storage virtualization controller (SVC 2) (20), the physical storage device controller (PSD controller) (81) initiates a data flow switching procedure to change the primary controller of the physical storage device (PSD) (9) from the first storage virtualization controller (SVC 1) (10) to the second storage virtualization controller (SVC 2) (20), and the data flow switching procedure includes generating a second selection signal to control the selector (83) to select data and signals from the second storage virtualization controller (SVC 2) (20).