Abstract: A method of controlling access from a virtual machine executed in a server device to a storage device, the method including acquiring a service level corresponding to a virtual machine identifier that identifies a virtual machine and is output from the virtual machine together with an input/output command by using the virtual machine identifier and by referring to a storage device that stores correspondence relationship between the virtual machine identifier and the service level and executing the input/output command from the virtual machine in accordance with the acquired service level in at least either the server device or the storage device.

Abstract: A method of controlling access from a virtual machine executed in a server device to a storage device, the method including acquiring a service level corresponding to a virtual machine identifier that identifies a virtual machine and is output from the virtual machine together with an input/output command by using the virtual machine identifier and by referring to a storage device that stores correspondence relationship between the virtual machine identifier and the service level and executing the input/output command from the virtual machine in accordance with the acquired service level in at least either the server device or the storage device.

Abstract: A method of managing compressed data including a cache segment generating operation generating cache segments each representing data that is obtained by assembling plural pieces of data requested of writing, and a compressed segment generating operation generating compressed segments each representing data that is obtained by compressing each of the cache segments generated in said cache segment generating operation. The method also includes a compressed segment allocating operation allocating each of the compressed segments generated in said compressed segment generating operation to one or more compression sectors each representing a buffer having a predetermined length, and a compression sector recording operation recording each of the compression sectors, on a disk storage device, to which at least one compressed segment is allocated in said compressed segment allocating operation.

Abstract: A method of managing compressed data in a disk storage device, including forming compressed segment areas in a continuous area according to a determined occupation ratio of the continuous area; obtaining a compression block corresponding to data to be stored in the disk storage device; deciding a compressed segment area to which the obtained compression block is to be stored according to a size of the obtained compression block; expanding the occupation ratio when an empty area in any of the compressed segment areas becomes less than a predetermined threshold value; and changing the occupation ratio of each compressed segment area of the continuous area according to the maintained record conditions of the compression blocks, dynamically, and based on an actual occupation ratio of compression blocks stored in each compressed segment area when an empty area in any of the compressed segment areas becomes less than a predetermined threshold value.

Abstract: An apparatus and method include allocating a compressed segment representing data that is obtained by assembling pieces of the data requested to write, and compressing the assembled data to a compression sector representing a block; changing, when updating content of the compressed segment in the compression sector recorded in said disk storage device, an area storing the compressed segment corresponding to an updating target into an invalid data area; comparing a size of the invalid data area in the compression sector recorded in said disk storage device with a preset fiducial value; and reading, from the disk storage device when the size of invalid data is larger than the preset fiducial value with respect to a certain compression sector, all of the compressed segments, exclusive of the invalid data, being allocated to the certain compression sector releasing a storage area of the storage device recording the certain compression sector.

Abstract: A disk control apparatus includes a host interface unit for inputting and outputting data from and to a host, a cache memory for temporarily storing the input data, a compression/decompression unit for compressing or restoring the input data and outputting the data, a buffer memory for temporarily storing the compressed data outputted from the compression/decompression unit, a disk access control unit for controlling an access to a disk and a disk data management unit for making a management as to which position of a disk storage device to write the data stored in the cache memory.

Abstract: A disk control apparatus includes a host interface unit for inputting and outputting data from and to a host, a cache memory for temporarily storing the input data, a compression/decompression unit for compressing or restoring the input data and outputting the data, a buffer memory for temporarily storing the compressed data outputted from the compression/decompression unit, a disk access control unit for controlling an access to a disk and a disk data management unit for making a management as to which position of a disk storage device to write the data stored in the cache memory.

Abstract: An apparatus including an input/output control device and an associated method are disclosed. The method includes a list with read requests recorded therein in the order of generation thereof is provided for each client, and a read request from a client is added to an end of a list for the client, when the request is generated within a specified period of time after generation of the previous read request from the same client. When the request is generated after passage of the specified period of time, it is added to a header of a new list. Common sections of the two lists are recorded in a common table, and information instructing to refer to the common table is inserted into the lists in place of the common sections in the lists. Data is prefetched from the disk device and stored in a cache memory based on the content of the lists. Data corresponding to common sections between the two lists may be relocated or written in a continuous empty area of the disk device in a continuous state.

Abstract: A disk control apparatus includes a host interface unit for inputting and outputting data from and to a host, a cache memory for temporarily storing the input data, a compression/decompression unit for compressing or restoring the input data and outputting the data, a buffer memory for temporarily storing the compressed data outputted from the compression/decompression unit, a disk access control unit for controlling an access to a disk and a disk data management unit for making a management as to which position of a disk storage device to write the data stored in the cache memory.

Abstract: A list with read requests recorded therein in the order of generation thereof is provided for each client, and a read request from a client is added to an end of a list for the client, when the request is generated within a specified period of time after generation of the previous read request from the same client. When the request is generated after passage of the specified period of time, it is added to a header of a new list. Common sections of the two lists are recorded in a common table, and information instructing to refer to the common table is inserted into the lists in place of the common sections in the lists. Data is prefetched from the disk device and stored in a cache memory based on the content of the lists. Data corresponding to common sections between the two lists is written in a continuous state in an empty area of the disk device.

Abstract: The logic blocks which were swept out from a non-compression cache memory are compressed by a compressing circuit and are combined to a compression group (logic sector size) of a fixed length in which a plurality of compression data are collected by a compression group forming unit. The compression group is stored into a logic sector of a disk drive through a compression cache memory. A correspondence relation with a plurality of logic blocks included in the logic sectors of a disk is registered in a mapping table. In response to a request by the logic block number from the host computer, the logic sector (compression group) of the disk drive is read and written with reference to the mapping table.