Abstract: A modular safety system for controlling emergency stop applications includes a plurality of inputs, a plurality of output groups, and a plurality of safe relay outputs. The plurality of inputs is assigned to at least one of the output groups. Each output group is configured to control at least one of the plurality of safe relay outputs. The system also includes means for configuring the system and at least three freely programmable output groups.

Abstract: A system and method for maintaining persistent data during an unexpected power loss uses a memory controller and a supplemental power source. An entity running on the computer, for example, an application program, a utility, the operating system or other entity, may identify data for preservation using an application program interface. The application program interface may be provided by the memory controller. A sensor determines when an unexpected power loss has occurred and signals the memory controller. Using power from the supplemental power source, i.e. a battery or capacitor, the memory controller copies the identified data to a non-volatile memory. The memory controller may set a flag to indicate that preserved data is available for later recovery.

Abstract: Techniques for identifying UPS-sub-system interconnections using manual data, UPS identification signals, and variations in UPS voltage variations that produce error signals. Once interconnections have been identified an operating system can check the UPS/sub-system topology to isolate potential errors and/or to enable controlled shut-down of sub-systems in case of potential power failure.

Abstract: A method of preventing failed field replaceable units (FRUs) directly connected to an interprocessor bus or fabric from interfering with the operation of a computer system during concurrent maintenance operations. When a FRU fails a concurrent maintenance operation, the service processor stores identification information corresponding to the failed FRU in an alert fail registry or a hot add fail registry and reports the failure status to a user. When a user attempts to perform a new concurrent maintenance operation on a FRU, the service processor compares that FRU to the alert fail registry or the hot add fail registry. If a concurrent maintenance operation on the requested FRU would cause a system crash due to interference with the failed FRU, the service processor notifies the repair and verify application (which notifies the user) and prevents concurrent maintenance operations from occurring on the new FRU.

Abstract: Embodiments include methods, apparatus, and systems for containing machine check events in a virtual partition. One embodiment is a method of software execution. The method divides a hard partition into first and second virtual partitions and attempts to correct an error in a firmware layer of the first virtual partition.

Abstract: An information processing apparatus having a resume function which can maintain the security even when a plurality of users commonly use the apparatus. A work state at a power-off time of the apparatus is preserved together with a work state name including a user's ID in a different area in a plurality of preservation areas for resume function on a main memory for each user. When a power source is again turned on, data in the preservation area corresponding to the user's ID is used to reproduce the work state of the user at the power-off time. The work preservation areas can be provided on a file server apparatus in a network not needing battery back-up. When the information processing apparatus is used, a work state at a power-off time can be independently preserved and reproduced for each user.

Abstract: An operation detecting part detects operation of a power switch, and a backup device performs a backup operation enabling a predetermined amount of power supply even after the power switch has cut off the power supply. Upon detection of power cut off by the operation detecting part, while the backup device performs the backup operation, the control part saves predetermined data stored in a volatile storage device in an apparatus externally via a network, or into a non-volatile storage device.

Abstract: Systems, methodologies, media, and other embodiments associated with power management are described. One exemplary system embodiment includes an uninterrupted power supply (UPS) manager logic configured to determine a power status of one or more UPS devices attached to one or more external peripheral devices. The UPS manager logic can be configured to notify an appropriate operating system of a power loss to a selected external device.

Abstract: A transactional file system developed to function with flash memory is described. The file system performs power-failure detection and ensures data integrity in the event of a power failure. In one described implementation, a power failure event can be detected by a file system, components of the file system, or individual modules in the form or computer-executable instructions and/or logic. Meta-information is stored at a location on a flash medium indicated by a write pointer if a computer device shuts-down according to a normal shutdown mode. During initialization of the computer, a check is performed whether the meta-information is present in the location on the flash medium indicated by the write pointer. If the meta-information is present, then a conclusion is made that the computer shutdown according to the normal shutdown mode.

Abstract: A method for deferred logging of machine data following an error or event in order to capture critical information for that error or event treats the data as persistent and it does not get logged until a disruption occurs to the system (e.g. system reset, restart, deactivation, or powered-down). This way, important debug data can be held in the hardware or software, without a need for complicated hardware and code for logging this debug data. Methods are also disclosed for setting a switch to indicate deferred logging is required, referencing the log data with the original event information, calling home with the debug data, resetting the deferred logging switch, setting the deferred logging switch manually, viewing whether the switch is already set, and supporting different kinds of switches.

Abstract: A transactional file system developed to function with flash memory is described. The file system performs power-failure detection and ensures data integrity in the event of a power failure. In one described implementation, a power failure event can be detected by a file system, components of the file system, or individual modules in the form or computer-executable instructions and/or logic. Meta-information is stored at a location on a flash medium indicated by a write pointer if a computer device shuts-down according to a normal shutdown mode. During initialization of the computer, a check is performed whether the meta-information is present in the location on the flash medium indicated by the write pointer. If the meta-information is present, then a conclusion is made that the computer shutdown according to the normal shutdown mode.

Abstract: An open-loop and closed-loop control unit for a safety-relevant apparatus, in particular for aviation applications, has a computer unit with a number of computer inputs and computer outputs, and a circuit unit with a number of circuit inputs and circuit outputs. The circuit unit has hardware components for simulating some of the logic operations that can be carried out in the computer unit. The circuit inputs and computer inputs that correspond to one another with respect to the simulated logic operations are each connected in parallel to a signal input line. The computer outputs and circuit outputs which correspond to one another with respect to the simulated logic operations are each connected to a decision-making unit, by which an output signal for open-loop control of the safety-relevant apparatus can be emitted as a function of the correspondence between the signals from the computer output and from the circuit output.

Abstract: The present invention is directed to suppress data loss caused by power shut-down during a rewriting process and to shorten time required to make a depletion check. A nonvolatile memory apparatus includes a rewritable nonvolatile memory and a card controller. The nonvolatile memory has a physical address area corresponding to a logical address and a save area. In response to a data rewrite instruction on a required logical address, the card controller stores data in a predetermined physical address area corresponding to the logical address to the save area and rewrites the data stored in the physical address area. When rewriting of the physical address area is incomplete, the card controller rewrites the data in the physical address area with the data stored in the save area. Thus, data loss caused by the power shut-down can be suppressed by data backup, and it is sufficient to make the depletion check in two places of the save area and the physical address area.

Abstract: Certain exemplary embodiments of the present invention provide a control system device, comprising a multiple channel discrete output module, said module storing a plurality of fail-state parameters, each fail-state parameter from the plurality of fail-state parameters corresponding to one channel of the multiple channels. Certain exemplary embodiments of the present invention provide a method for controlling the operation of each of a plurality of channels coupled to a discrete output module upon failure or shutdown of a control system coupled to the discrete output module, comprising, for each of the plurality of channels, storing a predetermined value for a fail-state parameter in a multi-channel discrete output module adapted to control the channel; and upon detecting a control system failure or shutdown, causing the channel to operate in a mode corresponding to the stored value for the channel's fail-state parameter.

Abstract: This invention provides a method to operate a terminal (100), as well as a terminal that operates in accordance with the method. The method includes, in response to initiating a data write operation with a non-volatile memory device (132), activating a sensor (190) that is capable of detecting that the terminal is falling; during the write operation, monitoring the sensor to determine if the terminal is falling and, if it is determined that the terminal is falling, terminating the write operation and executing a non-volatile memory shutdown procedure, else, if it is determined that the terminal is not falling, completing the write operation and deactivating the sensor.

Abstract: The invention is a hardware switching apparatus for initiating a soft power-down and a remote power-up in a computer system. The apparatus includes a power supply, a switching device having a first switch position and a second switch position, a switching circuit, and a wiring harness for remotely controlling the switching circuit. The power supply senses the power delivered from a primary source and produces a power-down signal when the power is interrupted. When the switching device is in the first switch position, the switching circuit is adapted to cause the power supply to produce a power-down signal. When the switching device is in the second switch position, the switching circuit is adapted to cause the power supply to produce a start-up signal.

Abstract: A memory dump program boot method includes the steps of defining, in non-volatile variables that are managed by a boot firmware of a computer system, boot information of a plurality of stand-alone dump programs that are installed in the computer system, and a table variable indicating a corresponding relationship of the plurality of stand-alone dump programs and a plurality of operating systems, specifying the boot information of a corresponding one of the plurality of stand-alone dump programs from the table variables when the boot firmware boots an arbitrary one of the plurality of operating systems, and writing information indicating the specified boot information in the non-volatile variables that are referred to when executing a stand-alone dump, and booting the corresponding one of the plurality of stand-alone dump programs when a booting of the stand-alone dump is instructed, by checking existence of variables that are referred to when executing the stand-alone dump and referring to information of the

Abstract: The invention provides a method and system for re-establishing sessions between a server and its clients following a failure of the server, planned reboot of the server, or takeover by another server. At critical points within a server/client session, state is saved so as to be reliable and consistent. Upon reboot of the system, state is restored using that which was saved; returning the server to its pre-crash state and preserving sessions that were in progress prior to the reboot. Additionally, state saved by a first sever prior to failure or elective shutdown can be transferred to a second server in a takeover configuration also preserving sessions in progress.

Abstract: A process plant includes a process control system having a safety system embedded therein. The integrated process control and safety system includes a host computer arranged to send and receive process level messages and safety level messages, a controller operatively connected to the host computer by a first communication network, at least one first input/output device adapted for operative communication with at least one process control field device, and at least one second input/output device adapted for operative communication with at least one safety-related field device. The first and second input/output devices are operatively connected to the controller via a second communication bus.

Abstract: With a storage system including a drive and a controller, which are connected to each other via cables, and with a method for controlling the storage system, an emergency power supply voltage for a power failure at the drive is multiplexed at the controller with a first signal to be sent to the drive, and the resultant emergency power supply voltage is sent via the cable to the drive. When a power failure occurs at the drive, the drive is powered with the emergency power supply voltage sent from the controller, and specified power failure information is multiplexed at the drive with a second signal to be sent to the controller, and the resultant power failure information is then sent via the cable to the controller; and specified processing is executed at the controller in response to the power failure information sent from the drive via the cable.

Abstract: Methods and apparatuses that automatically determine the capabilities of UPS devices. Systems automatically determine whether a UPS device is capable of protecting system resources by comparing the UPS capabilities against system requirements. Such systems can use that determination to approximate how long a UPS device can reliably supply power. Systems having multiple UPS devices can be implemented such that the connections of the UPS devices to system resources are automatically determined, the load on each UPS device can be found, the capabilities of the UPS devices can be obtained, a comparison between UPS load and UPS capabilities can made, and a warning of problems can be sent. Using UPS capability and load information a system can provide for a controlled shutdown of system resources.

Abstract: A method, a management node and a server for maintaining the server, which comprises a plurality of function boards, comprising steps and capabilities for receiving at the server a shutdown request comprising an identifier of at least one function board from the plurality of function boards, prior to executing the shutdown of the at least one function board, identifying at least one service associated with the at least one function board and sending a service notification comprising an identifier of the at least one service associated with the at least one function board. Further steps and capabilities are included for receiving a decision notification comprising one of a shutdown decision and a cancel shutdown decision, the shutdown decision and the cancel shutdown decision being taken considering the sent service notification and, if the decision notification comprises the decision to shutdown, shutting down the at least one function board.

Abstract: A method and an apparatus for performing high-quality read and write operations through a simple operation without being affected by an interruption even when the interruption has occurred in the course of a read/write operation between information storage media. When an interruption occurs in the course of reading program information stored on an optical disc to write the program information onto a hard disk, the write status of the program information which has encountered the interruption and the information for identifying the program information are stored on the hard disk. After the recovery from the interruption, read and write operations are restarted. Then, the program information capable of ensuring the continuity with the program information which has been properly written on the hard disk prior to the interruption is determined in accordance with the write status of the program information which has encountered the interruption and the information for identifying the program information.

Abstract: A system, method and software for reporting logical volume information on software RAID (redundant array of independent disks) enabled storage devices is disclosed. In one embodiment, a volume manager may be queried to identify one or more software RAID volumes and to determine their operating state. The information handling system's operating system may be queried to identify the storage devices included on the system and their operating state. After correlating the software RAID volumes to respective storage devices, a worst case operating state between the software RAID volumes and the storage devices may be reported to a light emitting diode (LED) driver. The LED driver may then command one or more chassis LED to illuminate in a manner that communicates the worst case operating state of one or more of software RAID volumes.

Abstract: A system is provided with a basic input/output system (BIOS) with the ability to intervene, when a suspend process is initiated in response to an AC failure condition to place the system in a suspended to memory state, to initiate a number of data transfer operations to save a persistent copy of an operational state of the system. The BIOS is further equipped to check one or more times whether the data transfer operations are completed, and causing a processor of the system to operate in a reduced power consumption mode at least one time period while the BIOS is not performing the checking.

Abstract: The disk array device supplies appropriate power to various parts in accordance with the operating mode in cases where the output of the main power supply drops. The disk array device adjusts the power from a commercial power source 6 with an AC/DC power supply 5, and supplies this power to a power supply common bus 7. A disk drive group 1 and a control circuit board group 2 constituting electrical loads are respectively connected to the power supply common bus 7. When the supply of power from the main power supply stops, the capacitor box 3 supplies a relatively large current for a short time only, in order to retain data during an instantaneous power outage. Then, the battery boxes 4 supply power to the power supply common bus 7 for a relatively long period of time, in order to perform destage control and memory backup. The battery boxes 4 perform balancing control of the output current in order to suppress variation in the output current value among the battery boxes 4.

Abstract: A system including a processor is energized from a source which is subject to power failure. To allow the state of the system to be restored after the power failure, at least portions of the volatile data of the processor are stored in non-volatile electrically erasable programmable read-only memory (Eeprom). In order to effectuate the data transfer, storage capacitors must provide power to the Eeprom and to the processor. In order to minimize the amount of storage capacitance, the processor power is maintained only until the data to be stored is transferred to the buffer of the Eeprom. Eeprom power is maintained until after a later time at which the buffer transfers the data to non-volatile storage of the Eeprom.

Abstract: The present invention relates to a method of operating a data processing system, having a system context, comprising a first storage medium having a current system memory context, which includes data relating to the system context, and a second non-volatile storage medium; the system being operable in a plurality of states, each state having an associated level of system power consumption; and a power management system for saving the current system memory context to the second non-volatile storage medium in preparation for entering at least one of the plurality of states; the method comprising the steps of: storing an indication of whether the system has been shutdown correctly or incorrectly; outputting, during a working state of the plurality of states, data representing at least a portion of the current system memory context for storage on the second storage medium; determining, upon initialisation of the system, from the indication of whether the data processing system was shutdown correctly or incorrectl

Abstract: A system and method is described for checking the health status of a communication pathways between an EMS and a notification listener that receives notification signals from the EMS when changes have occurred in a downstream electronic system architecture.

Abstract: A system and method for the reliable firmware update of a disk connected to a fibre channel loop fabric allows the specified filers and other predetermined system devices connected to the fabric to be made aware of a firmware download to the target disk without need of a system broadcast message, and while avoiding an alert or error condition such as those encountered through an FC-AL reset request. The target disk returns a special downloading firmware reject code embedded in a low-level protocol that remains operative during a firmware download. This reject code is recognized by an accessing system device as indicating that the disk is currently downloading updated firmware. In this manner, having recognized the code, the system device holds any I/O operations with respect to the target disk for a given delay time. Thus, the system device does not misinterpret the unavailability of the disk as a failure, leading to an unwanted system-wide FC-AL reset state.

Abstract: Failsafe control circuit for electrical appliances whereby at least one electrical load (10) is activated, the control circuit comprising logic control means (1), operation switching means (8) between said electrical load (10) and a supply voltage (V), and a first drive circuit (6) which receives a first command signal (4) from the logic control means (1), said first drive circuit (6) acting on said operation switching means (8). It also comprises security switching means (9) between the electrical load (10) and the supply voltage (V), and a second drive circuit (7) which receives a second command signal (5) from the logic control means (1), said second drive circuit (7) acting on the security switching means (9) so that it closes said security switching means (9) only if said second command signal (5) is a pulse signal.

Abstract: A threshold detection circuit for developing a mode trigger signal includes an input that receives an input signal. In response to the input signal having approximately an input threshold value for a triggering time, the threshold detection circuit activates the mode trigger signal on an output. In response to the input signal being substantially different from the input threshold value or the input signal not having the input threshold value for the triggering time, the circuit deactivates the mode trigger signal. The threshold detection circuit may be contained in a variety of different mode detection circuits for detecting when an integrated circuit is to be placed in a test mode or other desired mode of operation, and such mode detection circuits may be contained in a variety of different types of integrated circuits, such as memory devices generally and SRAMs specifically.

Abstract: A protected dual purpose power/enter switch for an integrated receiver/decoder has a first relay and a second relay adapted for operative communication with a motherboard and with each other. A switch and a processor are in operative communication with the first relay. When the device is off, said switch is configured to activate the first and second relay to power up the device, and when said device is on, the first relay connects the switch to the processor as an enter switch. The switch may power off said device by entering a power off menu item displayed by said processor.

Abstract: A transactional file system developed to function with flash memory is described. The file system performs power-failure detection and ensures data integrity in the event of a power failure. In one described implementation, a power failure event can be detected by a file system, components of the file system, or individual modules in the form or computer-executable instructions and/or logic. Meta-information is stored at a location on a flash medium indicated by a write pointer if a computer device shuts-down according to a normal shutdown mode. During initialization of the computer, a check is performed whether the meta-information is present in the location on the flash medium indicated by the write pointer. If the meta-information is present, then a conclusion is made that the computer shutdown according to the normal shutdown mode.

Abstract: In a Constant Access Time Bounded (CATB) cache, if a dirty line in a search group of the cache is selected for eviction from the cache, marking the dirty line as evicted, selecting a replacement line from a reserve, and inserting the replacement line into the search group.

Abstract: Methods, systems, and articles of manufacture for preserving error data on a computing platform that lacks non-volatile storage (e.g., a “diskless” platform) are provided. In response to detecting a platform error (e.g., automatically by hardware, software, or manually by a user when a wait or loop condition is suspected), platform error data may be gathered and temporarily stored in volatile storage accessible on the platform. In order to preserve the platform error data in the event power is lost after the error, the platform error data is transferred to a target system with access to non-volatile storage. Once the target system indicates the platform error data has been stored in non-volatile storage, the volatile storage used to temporarily store the platform error data may be freed-up.

Abstract: Each processor in a multi-processor system is periodically interrupted for preempting the current thread for servicing of a watchdog thread during normal operation. Upon failing to service the watchdog thread over a grace period, a system watchdog initiates an orderly shutdown and reboot of the system. In order to prevent spinlocks from causing fake panics, if the current thread is holding one or more spinlocks when the interrupt occurs, then preemption is deferred until the thread releases the spinlocks. For diagnostic purposes, a count is kept of the number of times that preemption is deferred for each processor during each watchdog grace period.

Abstract: A Node Manager monitors the status of multiple servers. The Node Manager detects server failures, periodically monitors server health status, and performs server maintenance. When the Node Manager detects a server failure, it determines whether or not the server should be restarted. While periodically monitoring servers, the Node Manager may determine how often to trigger a health check, how long to wait for a response, and how to proceed if the server is deemed failed. The Node Manager may be controlled by an Administrative Server directly or by an external administrative agent. An administrative agent may control the Node Manager by interfacing with the Administrative Server. The Node Manager and AS may authenticate each other and encode their communications to each other for increased security.

Abstract: Disclosed are an error recovery method and system for use with a communication system having first and second nodes, each of said nodes having a receiver and a sender, the sender of the first node being connected to the receiver of the second node by a first cable, and the sender of the second node being connected to the receiver of the first node by a second cable. The method comprising the step of after one of the nodes detects an error, both of the nodes entering the same defined state. In particular, the receiver of the first node enters an error state, stays in the error state for a defined period of time T, and, after said defined period of time T, enters a wait state. Also, the sender of the first node sends to the receiver of the second node an error message for a defined period of time Te, and after the defined period of time Te, the sender of the first node enters an idle state.

Abstract: When the emergency stop button on the teaching pendant is pressed, the packet generating circuits 1 and 2 each prepare packet data relating to emergency stopping, and transmit this data to the robot control part by wireless communications via the transmission data switching circuit. Besides data indicating the need or lack of need for emergency stopping, a header or the like designating the packet receiving circuit to which the transmission is addressed is added to the packet data. The respective packet receiving circuits of the robot control part receive the respective sets of packet data in accordance with the designations of the headers.

Abstract: An image recording/reproducing apparatus includes a first device for reproducing data from a recording medium, a second device for recording the data reproduced by the first device, a data maintenance unit for controlling the operation of the first and the second devices, a power supply unit for supplying a power to the first and the second devices, a power control unit for controlling operation of the power supply unit, an error data detecting unit for detecting an error data among the data recorded in the second device, and a main control unit, which, upon receiving a power cut-off command, controls the data maintenance unit to stop the operation of the second device and delete the error data detected by the error data detecting unit. Then, with the deletion of the error data, the main control unit controls power control unit so that the power supply unit cuts off the power supply.

Abstract: A method, system and computer program product for implementing a fault tolerant sleep mode of operation. The system state information may be stored in a volatile memory and in a non-volatile storage unit prior to entering the sleep mode of operation. If a memory corruption event, e.g., power outage, brownout, power surge, occurs during the sleep mode of operation, then, upon receiving an invocation to resume to a normal mode of operation, the system state information stored in the non-volatile storage unit may be reloaded into the volatile memory. By reloading the system state information stored in the non-volatile storage into the volatile memory, the computer system may resume to a normal mode of operation from a sleep mode of operation without any corruption or loss of data.

Abstract: A method for recovering dirty write cache data after controller power loss or failure from one of two independently battery backed up and mirrored write caches. Two independent controllers jointly operate with a permanent data storage system. Each controller has a write cache that is a mirror of the write cache in the other controller. The primary controller resets a power down flag stored each write cache upon proper shutdown. The primary controller further increments and stores a configuration sequence number into each write cache upon proper shutdown. If a primary controller powers up and identifies that the write cache was not properly shutdown due to the state of the power down flag, it flushes the dirty data in the write cache only if the configuration sequence number contained in the write cache is the same as the configuration sequence number contained in the primary controller.

Abstract: Certain exemplary embodiments of the present invention provide a control system device, comprising a multiple channel discrete output module, said module storing a plurality of fail-state parameters, each fail-state parameter from the plurality of fail-state parameters corresponding to one channel of the multiple channels. Certain exemplary embodiments of the present invention provide a method for controlling the operation of each of a plurality of channels coupled to a discrete output module upon failure or shutdown of a control system coupled to the discrete output module, comprising, for each of the plurality of channels, storing a predetermined value for a fail-state parameter in a multi-channel discrete output module adapted to control the channel; and upon detecting a control system failure or shutdown, causing the channel to operate in a mode corresponding to the stored value for the channel's fail-state parameter.

Abstract: A transactional file system developed to function with flash memory is described. The file system provides for efficient storage of file system meta-information, performs robust transaction logging, and performs other related features. In one described implementation, metadata is stored in-line with data. In another embodiment, a transaction log is maintained by storing transaction information associated with requests to perform file transactions. The transaction information is stored at arbitrary physical sector addresses on the flash medium. In still another embodiment, a transaction log is stored in a physical sector of a flash medium. The transaction log contains transaction information associated with performing a file request. Metadata is written into a spare area of the physical sector indicating that the physical sector contains transaction information.

Abstract: A disk array device having two or more disk units, each disk unit including at least one disk drive, at least either of said disk units having parity bits carrying data recovery information, comprises at least one backup battery provided for each of said disk unit.

Abstract: A method and a system for obtaining shutdown information for a computer allows a user to indicate a reason or reasons for the shutdown. The states of the user mode processes that are running on the computer are saved for later analysis. The state information as well as the shutdown reason entered by the user is stored in a computer-readable memory, such as in the form of a log file. A user may report a shutdown reason by selecting a reason from a predefined reason list and/or by typing a reason in a comment area.

Abstract: The present invention relates to a power failure recovery mechanism for a recording and reproducing device such as a DVD player, wherein a recording indication information and a recovery pointer information is written in a non-volatile random access memory, while a recovery information is recorded on a record carrier such as a recordable optical disc. At a power-up operation, the recording indication information is used to determine a power failure and the pointer information is used to reproduce the recovery information in case of a determined power failure. Thus, the pointer information indicates the location of incremental recovery data structures on the record carrier, such that a recovery can be achieved after a power failure without requiring a restart of the entire recording.

Abstract: Systems and methods consistent with the present invention provide for remote tracking of the reboot status for a plurality of user terminals. Each user terminal runs a start-up routine capable of creating a record of information about the terminal, including reboot status. The record of information is stored in log file on a file server, along with the records of information from other user terminals. A collection routine executed by a central server collects the log files from the file servers and stores the records in a database. Based on the records stored in the database, various status reports may be generated that reflect, among other things, a reboot status associated with the user terminals over a predetermined period of time.

Abstract: An external storage device 110 includes a semiconductor memory 200, a hard disk 210 having an access speed lower than that of the semiconductor memory 200, a judgment part 275 for determining whether or not data can be stored in the semiconductor memory 200, and an access processing part 277 for compressing and storing data into the semiconductor memory 200 after it is determined that the data can be stored in the semiconductor memory 200, and for storing the write data into the hard disk 210 when it is determined that the data cannot be stored in the semiconductor memory 200. The storage capacity of the external storage device 110 is larger than the storage capacity of the semiconductor memory 200.