Abstract: High reliability is achieved against hardware failures by use of logical computers. In plural logical computers using computers comprising plural physical processors, in cases where a highly reliable system is built using the plural logical computers, the logical computers are assigned to different physical processors. During failure recovery, reduction in service is prevented by increasing processor amounts of other active logical computers of the highly reliable system.

Abstract: A storage subsystem which includes a plurality of disk controllers, a plurality of disk drives connected via a network to the plurality of disk controllers, and a path controller connected to the plurality of disk controllers. The path controller changes a management site, which manages a volume in each disk drive managed by each disk controller, from one disk controller to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each disk drive and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: A storage subsystem which includes a plurality of disk controllers, a plurality of disk drives connected via a network to the plurality of disk controllers, and a path controller connected to the plurality of disk controllers. The path controller changes a management site which manages a volume in each disk drive managed by each disk controller, from one disk controller to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each disk drive and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: A storage subsystem which includes a plurality of disk controllers, a plurality of disk drives connected via a network to the plurality of disk controllers, and a path controller connected to the plurality of disk controllers. The path controller changes a management site which manages a volume in each disk drive managed by each disk controller, from one disk controller to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each disk drive and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: In a disk array system of RAID (level 5) improving the system performance by distributing data, duplicated fields are allocated in a parity group in order to reduce an overhead of data write. In the data write process, write data is tentatively and duplicately written in the duplicate fields. At this time, a write completion is reported to CPU. The parity is generated later at a proper timing and written in a SCSI drive. Generating a parity and writing data can be efficiently scheduled.

Abstract: A Database Management System (DBMS) of a main host system is directed by its agent to overwrite database table data (DB table data), which is stored in a DB buffer and put in and out by the DBMS, to the database table (DB table) on a main disk unit, and holds the updating of the DB table data in the DB table against a subsequent request of updating. A main disk control unit is directed by the agent to transfer the DB table data in the DB table to a DB table on a subordinate disk unit by a subordinate disk control unit to duplicate the DB table data, and suspend the subsequent transfer of DB table data so that the DB table data on both disk units are in a state of matching, thereby enabling the DBMS of the subordinate host system to refer to the copied DB table.

Abstract: A storage subsystem which includes a plurality of disk controllers, a plurality of disk drives connected via a network to the plurality of disk controllers, and a path controller connected to the plurality of disk controllers. The path controller changes a management site which manages a volume in each disk drive managed by each disk controller, from one disk controller to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each disk drive and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: In a disk array system of RAID (level 5) improving the system performance by distributing data, duplicated fields are allocated in a parity group in order to reduce an overhead of data write. In the data write process, write data is tentatively and duplicately written in the duplicate fields. At this time, a write completion is reported to CPU. The parity is generated later at a proper timing and written in a SCSI drive. Generating a parity and writing data can be efficiently scheduled.

Abstract: In a duplicated storage subsystem, a Database Management System (DBMS) of a main host system is directed by its agent to overwrite database table data (DB table data), which is stored in a DB buffer and put in and out by the DBMS, to the database table (DB table) on a main disk unit, and holds the updating of the DB table data in the DB table against a subsequent request of updating. A main disk control unit of the main disk unit is directed by the agent to transfer the DB table data in the DB table to a DB table on a subordinate disk unit by way of a subordinate disk control unit thereby to duplicate the DB table data, and suspends the subsequent transfer of DB table data so that the DB table data on both disk units are in a state of matching, thereby enabling the DBMS of the subordinate host system to refer a copied DB table in a state of matching.

Abstract: A storage subsystem which includes a plurality of disk controllers, a plurality of disk drives connected via a network to the plurality of disk controllers, and a path controller connected to the plurality of disk controllers. The path controller changes a management site, which manages a volume in each disk drive managed by each disk controller, from one disk controller to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each disk drive and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: A storage subsystem include: a plurality of disk controllers; a plurality of disk drives connected via a network to the plurality of disk controllers; and a path controller connected to the plurality of disk controllers. The path controller changes a management site, which manages a volume in each of the plurality of disk drives managed by each of the plurality of disk controllers, from one of the plurality of disk controllers to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each of the plurality of disk drives and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: A disk storage device comprising; a disk controller for accessing a disk storage medium to read/write data thereon, an object management program for converting a control command containing an object identifier received through a network interface into a control command containing physical address information of the disk storage medium and for feeding the thus converted control command to the disk controller, an object management modification program for modifying a function of the object management program in response to a modification request message received through the network interface, and a processor for carrying out these programs.

Abstract: Disclosed herein is a method for correcting programs without discontinuing service that is running on a logical computer. A patch manager 109 copies programs and data under control of a logical computer 1 (105) from one disk to another disk and activates a logical computer 2 (106). The logical computer 2 (106) corrects the copied programs by using a correction program in the copied programs. Then, the patch manager 109 switches control of a network from the logical computer 1 (105) to the logical computer 2 (106) in order to switch operation from the logical computer 1 (105) to the logical computer 2 (106).

Abstract: A communication controller at the sending computer divides data transferred from a host into sub-ACK unit packets, and transfers them sequentially to a destination without waiting for the sub-ACK's being subsequently provided by the destination. A communication controller at the receiving computer issues a sub-ACK to the sending computer for each of the sub-ACK unit packet, if the sub-ACK packet has been normally received and otherwise issues retransmission request for the sub-ACK unit packets and merges data included in the sub-ACK unit packets into the initial data, after they are normally received.

Abstract: A storage subsystem which includes a plurality of disk controllers, a plurality of disk drives connected via a network to the plurality of disk controllers, and a path controller connected to the plurality of disk controllers. The path controller changes a management site, which manages a volume in each disk drive managed by each disk controller, from one disk controller to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each disk drive and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: A communication controller at the sending computer divides data transferred from a host into sub-ACK unit packets, and transfers them sequentially to a destination without waiting for the sub-ACK's being subsequently provided by the destination. A communication controller at the receiving computer issues a sub-ACK to the sending computer for each of the sub-ACK unit packet, if the sub-ACK packet has been normally received and otherwise issues retransmission request for the sub-ACK unit packets and merges data included in the sub-ACK unit packets into the initial data, after they are normally received.

Abstract: A disk storage device comprising; a disk controller for accessing a disk storage medium to read/write data thereon, an object management program for converting a control command containing an object identifier received through a network interface into a control command containing physical address information of the disk storage medium and for feeding the thus converted control command to the disk controller, an object management modification program for modifying a function of the object management program in response to a modification request message received through the network interface, and a processor for carrying out these programs.

Abstract: An information processing system which reduces an access latency from a memory read request of a processor to a response thereto and also prevents reduction of the effective performance of a system bus caused by an increase in the access latency. In the information processing system, a memory controller is connected with the processor via a first bus and connected with a memory via a second bus, and a buffer memory is provided in the memory controller. The control circuit is controlled, before a memory access from the processor is carried out, to estimate an address to be possibly next accessed on the basis of addresses accessed in the past and to prefetch into the buffer memory, data stored in an address area continuous to the address and having a data size of twice or more an access unit of the processor.

Abstract: A storage subsystem include: a plurality of disk controllers; a plurality of disk drives connected via a network to the plurality of disk controllers; and a path controller connected to the plurality of disk controllers. The path controller changes a management site, which manages a volume in each of the plurality of disk drives managed by each of the plurality of disk controllers, from one of the plurality of disk controllers to another. The path controller has a correspondence table which stores a correspondence between a volume number of a volume in each of the plurality of disk drives and identification information of the disk controller which manages a volume corresponding to the volume number.

Abstract: An information processing system which reduces an access latency from a memory read request of a processor to a response thereto and also prevents reduction of the effective performance of a system bus caused by an increase in the access latency. In the information processing system, a memory controller is connected with the processor via a first bus and connected with a memory via a second bus, and a buffer memory is provided in the memory controller. The control circuit is controlled, before a memory access from the processor is carried out, to estimate an address to be possibly next accessed on the basis of addresses accessed in the past and to prefetch into the buffer memory, data stored in an address area continuous to the address and having a data size of twice or more an access unit of the processor.