Abstract: According to one embodiment, a storage device includes a storage, first data in which a sequence number indicating a write-completion order is associated with each erase unit area included in areas of the storage, second data indicating a relationship between each write interval and each write destination, a selection module which obtains the erase unit area corresponding to a logical address of target data to be written, calculates a write interval of the target data from a difference between the sequence number at an occurrence time of writing and the sequence number corresponding to the erase unit area of the first data, and selects the write destination corresponding to the write interval of the target data, and a write module which writes the target data to the selected write destination, and changes the sequence number when writing is completed for one erase unit area.

Abstract: In an embodiment, a storage device includes a shingled magnetic recording device, a management unit, selection unit, and execution unit. The shingled magnetic recording device performs writing in unit of a band including tracks being adjacent to and partially overlapping with each other. The management unit manages management information mutually associating band identifier of the band, characteristic information indicating a possibility that data stored in the band is not referred to, and data identifier of the data in a case where the data is stored in the band. The selection unit selects the band of the shingled magnetic recording device storing the data based on the data and the characteristic information in a case where the shingled magnetic recording device is requested to store the data. The execution unit stores the data to the selected band.

Abstract: In an embodiment, a storage device includes a shingled magnetic recording device, a management unit, selection unit, and execution unit. The shingled magnetic recording device performs writing in unit of a band including tracks being adjacent to and partially overlapping with each other. The management unit manages management information mutually associating band identifier of the band, characteristic information indicating a possibility that data stored in the band is not referred to, and data identifier of the data in a case where the data is stored in the band. The selection unit selects the band of the shingled magnetic recording device storing the data based on the data and the characteristic information in a case where the shingled magnetic recording device is requested to store the data. The execution unit stores the data to the selected band.

Abstract: According to one embodiment, a storage device includes a storage, first data in which a sequence number indicating a write-completion order is associated with each erase unit area included in areas of the storage, second data indicating a relationship between each write interval and each write destination, a selection module which obtains the erase unit area corresponding to a logical address of target data to be written, calculates a write interval of the target data from a difference between the sequence number at an occurrence time of writing and the sequence number corresponding to the erase unit area of the first data, and selects the write destination corresponding to the write interval of the target data, and a write module which writes the target data to the selected write destination, and changes the sequence number when writing is completed for one erase unit area.

Abstract: A user private key is stored in a database of the user terminal. A user public key and user information are stored in the user management DB. The encryption/decryption unit encrypts an authority private key specific to a first authority given to a user, by using a user public key associated with user information to indicate a user. The secret sharing unit shares in secret an authority private key into two or more shared authority private keys. The encryption/decryption unit encrypts the shared authority private keys, by using an authority public key specific to each of second authorities to manage the first authority in a shared manner. The authority management DB stores the encrypted authority private key and authority public key in association with the first authority, and stores the encrypted shared authority private keys in association with the second authorities.

Abstract: A user private key is stored in a database of the user terminal. A user public key and user information are stored in the user management DB. The encryption/decryption unit encrypts an authority private key specific to a first authority given to a user, by using a user public key associated with user information to indicate a user. The secret sharing unit shares in secret an authority private key into two or more shared authority private keys. The encryption/decryption unit encrypts the shared authority private keys, by using an authority public key specific to each of second authorities to manage the first authority in a shared manner. The authority management DB stores the encrypted authority private key and authority public key in association with the first authority, and stores the encrypted shared authority private keys in association with the second authorities.

Abstract: Snapshot management means intervenes between a file system for managing access, including update, to files stored in nonvolatile storage devices and the nonvolatile storage devices. The snapshot management means creates a snapshot holding the contents of the files at a specific point in time for each of the nonvolatile storage devices and stores the created snapshot into the corresponding nonvolatile storage device. The configuration makes it possible to create snapshots effectively without any modification to application programs or a file system.

Abstract: A disk storage system with a RAID architecture, where the disk memory has N units of disks, includes a control unit to write data to the N units of disks or read data therefrom based on instructions from a host equipment, a volatile memory connected to the control unit, and a non-volatile memory connected to the control unit. The volatile memory includes a time stamp memory and a conversion map. The non-volatile memory includes a write buffer, which has a capacity of N×K logical block data (N is a positive integer not less than 2 and K is an integer indicating the number of blocks), and a buffer management table. The control unit accumulates logical block data to be updated in the write buffer until the number of logical blocks reaches N×K−1. It generates logical address tag blocks, including time stamps stored in the time stamp memory and adds them to the N×K−1 logical blocks.

Abstract: An optical interconnection capable of realizing smooth data transmissions among micro-processors provided on a plurality of processor boards. An optical interconnection includes: a series of optical devices, provided on the processor boards separately, each optical device on each processor board being connected with the processor elements provided on that processor board and including a multiplicity of optical element cells for intercepting light signals from a first side of the optical device, transmitting intercepted light signals to a second side of the optical device, and emitting light signals to the second side of the optical device; and an optical path for optically connecting the optical devices such that light signals coming from the second side of one optical device are intercepted at the first side of another optical device.