Magnetic disk subsystem with failsafe battery charging and power shut down

A magnetic disk apparatus comprising magnetic disk modules connected under the control of magnetic disk control means, power units which convert input voltage from an outside power supply to a predetermined DC voltage and supply the same to the magnetic disk modules, magnetic disk module battery units which supply the magnetic disk modules with the same DC voltage as the power units, and power control means which control the input and cut-off of the power of the power units and the magnetic disk modules, and detect a power failure, wherein said magnetic disk apparatus further includes:

• the magnetic disk module battery units including charging completion detecting means which judge the completion of charging of the battery units accommodated when a charging current becomes less than a predetermined value and output a charging completion notification signal to the power control means;
• and
• the power control means detecting a power failure after the charging completion detecting means detected the completion of charging, and including a charging completion invalidating means which invalidates the charging completion detection signal output from the charging completion detecting means at the time of detecting the power failure, whereby
• when the charging completion notification signal is output while the charging current falls as a result of the power failure caused before the completion of charging, it can be judged that the charging has not yet been completed at the time of detection of the power failure.

A magnetic disk apparatus comprising a main power unit provided with power units which receive as input an AC power and convert the same to DC voltage, and battery units which are charged by the DC voltage of the power units and output the same DC voltage at the time of a power failure, magnetic disk modules which operate by receiving the power from the main power unit, a magnetic disk control unit which receives the power from the main power unit and controls the magnetic disk modules, and a power control unit which controls the input and cut-off of power from the main power unit to the magnetic disk modules and the magnetic disk control unit,

• the power control unit having;
• a power failure detecting means for detecting the stopping of the input of the AC power,
• a first timer which activates when the power failure detecting means detect a power failure, monitor the time during which the input of power has stopped, and produce a timer output when a first predetermined back-up time has been reached;
• and
• back-up control means for executing a power cut-off processing of the magnetic disk modules and the magnetic disk control unit on the basis of a power cut-off command which it received from a higher apparatus before the timer output of the first timer and for executing the power cut-off processing of the magnetic disk modules and the magnetic disk control unit when not receiving a command for power cut-off from the higher apparatus, but when the first timer output is obtained;
• wherein the back-up control means as part of the power cut-off processing of the magnetic disk modules and the magnetic disk control unit, output a power cut-off control signal to the magnetic disk control unit to cause the input and output operation of the magnetic disk unit to end and, when receiving a cut-off authorization notification signal on the basis of the end of the input and output operation from the magnetic disk control unit, cut off the power of the magnetic disk modules and the magnetic disk control unit.