Fujitsu Corporation

Hiroyuki Shimoi

Naoaki Okayasu

Shigeru Yoshida

Yoshiyuki Okada

Masanaga Tokuyo

Shigeru Honmura

Eiichi Yamanaka

Satoru Kaneko

Hidetomo Maeda

An information processing device detects a sequential access for reading first data by sequentially accessing consecutive areas or inconsecutive areas within a specified range of a first storage unit when the sequential access consecutively occurs by a specified number, calculates, based on a size of the first data, a size of second data read by a prefetch for prereading the data stored consecutively in the first storage unit and for storing the read data in a second storage unit, and performs the prefetch based on the calculated size of the second data.

Information processing device for detecting sequential accesses and prefetching

In order to provide a disk array access dynamic control device and a method for improving the performance of a disk array device, the disk array access dynamic control devicecomprises a composition information storage unitfor storing composition information, such as the combination information of disk devices constituting a RAID and the like, a responsible DA control unitfor assigning DAs according this composition information or the like and an access unitfor reading/writing data from/into a disk device groupaccording to the instruction of an information processing device

Disk array access dynamic control device and method

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.

Storage control apparatus and method for compressing data for disk storage

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.

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.

Compressed data managing apparatus and method therefor to manage compressed data of a disk storage

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.

Disk control apparatus for recording and reproducing compression data to

A data protection system for protecting data stored in a memory in a data processing system having at least a channel system, a device controller and an external storage device. The data protection system includes a memory provided in the device controller which receives a power source voltage, and temporarily stores data to be transferred. A battery is connected to the power source and the memory, is charged by the power source when the power source is normal, and supplies a battery voltage to the memory when the power source is accidentally interrupted. A first voltage check circuit is connected to the battery, compares the battery voltage with a first reference voltage, and generates a battery error signal when the battery voltage is lower than the first reference voltage. A second voltage check circuit is connected to the battery; compares the battery voltage with a second reference voltage and generates a battery charging signal when the battery voltage lies between the first and second reference voltages. A control circuit selectively determines two modes-one mode being a write-back mode for transferring data from the memory to the external storage device after data is stored in the memory, and the other being a write-through mode for directly transferring data from the channel system directly to the external storage device when one or both of the battery error signal and the battery charging signal is input thereto.

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Kawasaki, Japan

Hiroyuki Shimoi