Fujitsu Corporation

International Business Machines Corporation

Hirofumi Morita

Keiichi Yorimitsu

Takashi Ishida

Mikio Itoh

Stephen J Schmandt

Suijin Takeda

Katsuhiro Tanaka

Tomoyuki Suganuma

Hiroshi Hirai

Zenhachiroh Butoh

Keiji Amatsu

Nobuo Nomura

Takeo Nakajima

Mikio Sakaki

Minoru Massaki

A disk array device maintains data reliability with few performance degradation problems. In a RAID 4 or RAID 5 disk array device, redundant data created during disk degeneration with a device control module is transferred to a memory of a subsystem control module. The memory is backed up with a battery. The redundant data is held in memory until a writing operation to disk drives is completed. Then, when recovering after a momentary power supply interruption, the write data and parity data stored in the memory are written out without writing data from the disk drive. When recovering after a momentary power supply interruption and the disks are normal, the redundant same-group data is read from disk drives other than those on which the data that is to be written and the parity are stored and based on those and the write data, new redundant data is created and written to the object disk.

Disk array device including a memory with backup power supply and method thereof

The spare disk unit existing in the port other than the parity group to which a failure disk unit in a disk array belongs is most preferentially selected as an alternative destination and data is reconstructed. When a system is made operative, the spare disk unit is allocated to a different port position every rank and the spare disk unit belonging to the rank of the failure disk unit is most preferentially selected as an alternative destination. Due to this, the selection of the alternative destination by the spare disk unit is optimized and the deterioration of performance in data reconstruction is prevented.

Method and apparatus for taking countermeasure for failure of disk array

When an amount of write data instructed by an upper-level system is small, a plurality of disk units are accessed individually and data split in sectors is written therein (Level 5 RAID). When an amount of write data instructed by the upper-level system is large, the plurality of disk units are accessed in parallel and data split in sectors is written therein (Level 3 RAID). When a disk unit in an array, to which a setup instruction is issued according to a processing request sent from the upper-level system, returns a fault reply, an ID management table is used to allocate an auxiliary disk instead of the failing disk unit. After the allocation, data is restored to the replacement disk using the data in normal disk units in the same rank. In a dual-port access configuration, when two transactions access disk units connected to the same port, a deadlock may occur depending on the access procedure. It is checked if the conditions for a deadlock are established, so that access will be obtained according to a procedure for preventing or avoiding a deadlock.

Fault tolerant disk array system for allocating auxillary disks in place

Apparatus for controlling data writing into a disk array system

A distributed data processing system is provided in which two computers, each running under a different operating system, are coupled so that jobs initiated by a first one of the computers can be executed on a second computer by using the resources of the second computer. This enables the user of the first computer to use the second computer under the environment of the first computer. The first computer acts as the interface between the user and the data processing system. Service programs running on the system can handle or provide for input/output operations during the execution of jobs on the second computer so that the jobs seem to the user of the first computer to be executed on the first computer. The system has means for creating a dummy file in the file system of one operating system which is used as a place holder for a corresponding file in a storage device attached to the other operating system, and accessed by programs controlled by that other operating system.

Distributed data processing system having front-end and back-end

Growing community of inventors

Kawasaki, Japan

Hirofumi Morita