Abstract: An external storage system has a storage unit for storing data and a plurality of storage controllers for controlling data transfer between an upper level system and the storage unit. Each storage controller has a data buffer for temporarily storing data and a controller for controlling the operation of the storage controller. The external storage system has a management memory for storing management information of the plurality of storage controllers each of which accesses this memory to monitor the operation states of other storage controllers. The external storage system has a first storage controller for processing an input-output request from the upper level system and a second storage controller for standing by for backup for a failed storage controller.

Abstract: A vibrating member, including a vibration transmission shaft, is adapted to vibrate a liquid viscosity detector with respect to an axis of the shaft. The liquid viscosity detector is disposed at one end of the vibration transmission shaft so it can be dipped in a liquid to be measured. A bearing portion is disposed at an intermediate position of the vibration transmission shaft. The viscosity detector includes an inertia mass disposed on the vibration transmission shaft along the central axis thereof. The viscosity detector is positioned on the opposite side of the shaft relative to the liquid detector, with the bearing portion located therebetween. Also provided is a node alignment mechanism for displacing the whole inertia mass along the central axis of the shaft, or a part of the inertia mass toward or away from the shaft axis or along the direction of the axis.