International Business Machines Corporation

Compagnie Ibm France

James C Chen

Chung Man Fung

Chan Y Ng

Minh-Ngoc Le Huynh

Richard Anthony Ripberger

Patricia Ching Lu

Matthew J Kalos

Michael T Benhase

Gail Andrea Spear

Theodore Timothy Harris, Jr

Olympia Gluck

Christopher Michael Sansone

Dung Ngoc Dang

Gabriel G Walder

Thao Bich Bui

Warren Keith Stanley

Shih-Ming Shih

Joseph S Glider

Steven Edward Klein

Adalberto Guillermo Yanes

Mantle Man-Hon Yu

Edward Lin

William Henry Travis

Mark Steven Bayus

Alex Chen

Lloyd R Shipman, Jr

Jesse I Stamness

Richard Alan Schaeffer

William G Sherman, Ii

Yelena Zilberstein

Kaukab Uddin

James Richard Pollock

David C Giese

Julia Liu

Rufus J Twito

Charles Richard Lanzi

Frederick J Carberry

System and computer program product are provided to configure a path between nodes through a fabric in a fibre channel storage area network (SAN). A node name is provided for a target node on the SAN and a port name is provided for each port in the target node. A relationship is established in a data structure between each port name and a slot in which each port is physically located in the target node. Prior to configuring a path between a source node and a port in the target node, the ports which are physically connected and logged in to the fabric are identified by port address. The port names corresponding to the port addresses are then identified. The port names are used to generate interface_ids of the ports corresponding to the physical slots in which the ports are located. A data structure is created to maintain the relationship between interface_ids and port names. To establish a path connection between a port in the source node and a selected port in the target node, the node name of the target node and the interface_id of the selected port are input to the data structure and the port name of the selected port is output. The port name is then used to obtain the address of the selected port and an I/O session path opened between the source and target nodes.

Configuration of fibre channel SAN path

Methods, system and computer program product are provided to improve the efficiency of data transfers in a PPRC environment. Any or all of three features may be implemented, each of which reduces the number of round trips required for the exchange of handshaking, data and control information. A first feature includes disabling the 'transfer ready' acknowledgment which normally occurs between a primary storage controller and a secondary storage controller. A second feature includes pre-allocating payload and data buffers in the secondary storage controller. A third feature includes packaging write control information with a write command in an extended command descriptor block (CDB). Such a step eliminated the need for a separate transmission of the write control information. The CDB is transmitted along with a data block from the primary storage controller to the secondary storage controller and placed in the respective, pre-allocated buffers. Data may also be pipelined to the secondary. By decreasing the response time for data transfers, the distance separating the primary and secondary storage controllers may be increased.

Decreased response time for peer-to-peer remote copy write operation

Methods, system and computer program product are provided to configure a path between nodes through a fabric in a fibre channel storage area network (SAN). A node name is provided for a target node on the SAN and a port name is provided for each port in the target node. A relationship is established in a data structure between each port name and a slot in which each port is physically located in the target node. Prior to configuring a path between a source node and a port in the target node, the ports which are physically connected and logged in to the fabric are identified by port address. The port names corresponding to the port addresses are then identified. The port names are used to generate interface_ids of the ports corresponding to the physical slots in which the ports are located. A data structure is created to maintain the relationship between interface_ids and port names. To establish a path connection between a port in the source node and a selected port in the target node, the node name of the target node and the interface_id of the selected port are input to the data structure and the port name of the selected port is output. The port name is then used to obtain the address of the selected port and an I/O session path opened between the source and target nodes.

A method to provide information from a first information storage and retrieval system to a second information storage and retrieval system. Applicants' method provides a first information storage and retrieval system, where that first information storage and retrieval system comprises (N) PPRC adapters and information, and provides a second information storage and retrieval system. The method generates and saves an Established Path Bitmap which recites each of the (N) PPRC adapters, and generates an Available Path Bitmap. If a PPRC adapter is in communication with the secondary information storage and retrieval system, then the method adds that adapter to the Available Path Bitmap. The Established Path Bitmap and the Available Path Bitmap are used for subsequent PPRC operations.

Apparatus and method to provide information from a first information storage and retrieval system to a second information storage and retrieval system

A method to provide information from a first information storage and retrieval system to a second information storage and retrieval system, where the first information storage and retrieval system comprises (N) PPRC adapters and information. The method generates and saves an Established Path Bitmap which recites the (N) PPRC adapters, and generates an Available Path Bitmap. If a PPRC adapter is in communication with the secondary storage system, then the method adds that adapter to the Available Path Bitmap. The primary information storage and retrieval system generates a PPRC task comprising a flag set to 'off'. The method copies the Available Path Bitmap as a Working Bitmap, and generates a PPRC request comprising a flag set to 'on', selects one of the adapters recited in the Working Bitmap, and provides the PPRC request to that selected adapter. The method then once attempts to provide information to the second information storage and retrieval system using the selected adapter.

Apparatus and method to implement retry algorithms when providing information from a primary storage system to a remote storage system

A log-in resource release system includes a set of lists for managing log-in requests to a processing cluster input/output port from host server input/output ports. Host servers that have been granted memory structures within a memory storage device ('configured hosts') are granted priority access to a storage processing device's input/output port ('cluster port'). If the cluster port has exhausted its log-in resources, log-on requests from non-configured hosts will be not be accepted. New log-in requests from configured hosts will cause a host connected at a link or transport layer but not an upper layer to be logged off. If no hosts are connected only at the link or transport layer, a non-configured host connected at an upper layer will be logged off. If only configured hosts are connected and only at the upper layer, the log-on request by the configured host will be denied.

Log-in resource release system

A method of error management in a data storage system having a target device, with the target device receiving commands from a first initiator and the target device concurrently receiving commands from a second initiator. The target device is typically a storage device operating as a PPRC secondary. A first initiator is a device which communicates with the target device through small computer systems interface (SCSI) protocol. The first initiator is typically a host computer or server. The second initiator communicates with the target device through peer-to-peer remote copy PPRC initiator mode commands. The second initiator is typically a separate storage device in a peer-to-peer remote copy (PPRC) relationship with the target device. The method consists of managing errors associated with a command sent to the target device from the first initiator independently from the management of errors associated with a command sent to the target device from the second initiator.

Concurrent PPRC/FCP and host access to secondary PPRC/FCP device through independent error management

Computer networks are provided with a resource efficient ability to generate link performance statistics. Two counters accumulates the number of I/O operations processed by a link and the time required by the link to complete each I/O operation. The average link utilization per I/O operation may then be calculated. The number of operations per second for a link may be computed by dividing the output from the first counter by a predetermined period of time and the average number of operations using the link may be computed by dividing the output from the second counter by the predetermined period of time. An optional third counter may be employed to accumulate the number of bytes transferred by a link during each I/O operation and used to compute the average size of an I/O operation. The generated statistics are useful for such activities as problem resolution, load balancing and capacity planning.

Efficient accumulation of performance statistics in a multi-port network

Methods, system and computer program product are provided to improve the efficiency of data transfers in a PPRC environment. A block of data to be transferred is divided into tracks. Each track is allocated to a data mover task control block (TCB) with a master TCB being assigned to supervise the data mover TCBs. The tracks are then transferred from the primary storage controller to the secondary controller in a piped fashion over a link coupling the primary and secondary storage controllers. However, the usage of resources is monitored by a resource management algorithm and, if too many TCBs are being used for a transfer or if the supply of data mover TCBs is exhausted, the transfer is automatically switched to a serial, non-piped transfer with the master TCB serving as the data mover TCB for the remaining tracks. In addition, the various links coupling the primary and secondary storage controllers is monitored to determine which link will provide the fastest transfer. If, during a transfer of tracks over one link, a faster link is identified, the transfer may be switched to the second, faster link.

Bandwidth utilization in a PPRC system

Disclosed is a method, system, program, and data structure for queuing requests. Each request is associated with one of a plurality of priority levels. A queue is generated including a plurality of entries. Each entry corresponds to a priority level and a plurality of requests can be queued at one entry. When a new request having an associated priority is received to enqueue on the queue, a determination is made of an entry pointed to by a pointer. The priority associated with the new request is adjusted by a value such that the adjusted priority is associated with an entry different from the entry pointed to by the pointer. The new request is queued at one entry associated with the adjusted priority.

Method, system, program, and data structure for queuing requests having different priorities

A staging method and means for both device read and update write operations in which messages and commands between a storage subsystem and a fixed-block formatted RAID array emulating a variable-length record (CKD) formatted device for both read and write operations are evaluated to ascertain whether the record addressing was random and truly in record mode. If they are in that mode, then partial track staging by the RAID array control from the fixed-block formatted HDDs to a subsystem cache or the like would reduce device contention by reading and staging less than full track.

Method and means for reducing device contention by random accessing and partial track staging of records according to a first DASD format but device mapped according to a second DASD format

Method and means for reducing device contention by random accessing and

System and method aspects for avoiding data corruption during data transfer in a disk array environment are described. In a circuit aspect, an integrity checker includes counting logic for counting fields in the data being transferred. The integrity checker further includes comparison logic for comparing a constant value and a value in a predetermined field of data being transferred. Combinational logic is further included and coupled to the comparison logic and counting logic, wherein when the comparison logic results in a miscompare and the counting logic is at a predetermined count value, the integrity checker circuit aborts data transfer. In a method aspect, the method includes providing an integrity checker at an interface to an array of disk drives, and performing data validity determinations on data passing across the interface with the integrity checker, wherein invalid data is not transferred.

Method and circuit for data integrity verification during DASD data

A method and means within a hierarchical, demand/response DASD subsystem of the passive fault management type in which, upon the occurrence of fault, error, or erasure, a long device busy signal of finite duration is provided to a host CPU. Any DASD storage device subject to the anomaly is isolated from any host inquiry during this interval. These measures permit retry or other recovery procedures to be implemented transparent to the host and the executing application. This avoids premature declarations of faults, errors, or erasures and consequent host application aborts and other catastrophic measures. If the detected anomaly is not resolved within the allotted time, then other data recovery procedures can be invoked including device reset, the status reported to the host, and the next request processed.

Method and means for utilizing device long busy response for resolving

The present invention provides a method and system for detecting corrupted data of a plurality of hard disk drives (HDDs) in a data storage subsystem. In this system a predetermined number of fixed blocks within each of the HDDs emulate a track of a first track format. The predetermined number of fixed blocks provide a logical track. The logical track of one of the plurality of HDDs is generated by the others of the plurality of HDDs. The plurality of logical tracks forming a plurality of track groups. In a first aspect the method and system comprises assigning each of the plurality of logical tracks an address translation (ADT) number, comparing each of the ADT numbers of the plurality of logical tracks to an expected value until a mismatch occurs in a logical track, and determining if other logical tracks in a same track group have accurate ADT numbers. The first aspect further includes reconstructing the logical track if the other tracks within the same track group have accurate ADT numbers. In a second aspect the method and system comprises determining each of the plurality of logical tracks is formatted in accordance with first track format, comparing each of the formats of the plurality of logical tracks to the expected format until a mismatch occurs in a logical track, and determining if other logical tracks in a same track group have accurate first track formats. The second aspect includes reconstructing the logical track if the other tracks within the same track group have accurate first formats.

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Tucson, AZ, United States of America

James C Chen