Abstract: A primary data storage system is linked to a geographically remote secondary data storage system for automatically maintaining a remote copy of the data in the primary storage. Each of the data storage systems has at least one data storage device, a cache memory, a data storage system controller, and a service processor for servicing the data storage system. The primary and secondary service processors are linked to permit remote system configuration and remote software programming of the secondary data storage system, and to exchange a report of all the non-valid, out of sync tracks. The service processors can also perform the task of scanning for remote write pending bits to invoke the remote copy task, and checking for invalid track bits to invoke a task for copying data from a known good storage device to the device with the invalid track bit set.

Abstract: A data storage system wherein end-user data is transferred between a host computer and a bank of disk drives through an interface. The interface includes a memory and a plurality of directors interconnected through an interface state data bus and a plurality of end-user data busses. At least one front-end one of the directors is in communication with the host computer and at least one rear-end one of the directors is in communication with the bank of disk drives. The interface state data bus section is in communication with: both the at least one front-end one and the at least one rear-end one of the directors; and to the memory. Each one of the plurality of end-user data buses has a first end coupled to a corresponding one of the plurality of directors and a second end coupled to the memory.

Abstract: An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table and high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the requested data record, the system directly accesses the requested data record on the storage medium thereby minimizing storage medium search time.

Abstract: An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table in high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the requested data record, the system directly H: accesses the requested data record on the storage medium thereby minimizing storage medium search time.

Abstract: A data storage system wherein end-user data is transferred between a host computer and a bank of disk drives through an interface. The interface includes a memory and a plurality of directors interconnected through an interface state data bus and a plurality of end-user data busses. At least one front-end one of the directors is in communication with the host computer and at least one rear-end one of the directors is in communication with the bank of disk drives. The interface state data bus section is in communication with: both the at least one front-end one and the at least one rear-end one of the directors; and to the memory. Each one of the plurality of end-user data buses has a first end coupled to a corresponding one of the plurality of directors and a second end coupled to the memory.

Abstract: A data storage system wherein end-user data is transferred between a host computer and a bank of disk drives through an interface. The interface includes a memory and a plurality of directors interconnected through an interface state data bus and a plurality of end-user data busses. At least one front-end one of the directors is in communication with the host computer and at least one rear-end one of the directors is in communication with the bank of disk drives. The interface state data bus section is in communication with: both the at least one front-end one and the at least one rear-end one of the directors; and to the memory. Each one of the plurality of end-user data buses has a first end coupled to a corresponding one of the plurality of directors and a second end coupled to the memory.

Abstract: A method and apparatus for interfacing two ESCON compatible devices over a communication channel that is not dedicated solely to ESCON communication, such as a public communication network or links, for example, a T1 or T3 line. The devices may include a master storage device and a mirroring storage device disposed at remote locations. In one embodiment, the devices communicate using the ESCON protocol.

Abstract: An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table in high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the requested data record, the system directly accesses the requested data record on the storage medium thereby minimizing storage medium search time.

Abstract: A cache management system and method monitors and controls the contents of cache memory coupled to at least one host and at least one data storage device. A cache indexer maintains a current index of data elements which are stored in cache memory. A sequential data access indicator, responsive to the cache index and to a user selectable sequential data access threshold, determines that a sequential data access is in progress for a given process and provides an indication of the same. The system and method allocate a micro-cache memory to any process performing a sequential data access. In response to the indication of a sequential data access in progress and to a user selectable maximum number of data elements to be prefetched, a data retrieval requestor requests retrieval of up to the selected maximum number of data elements from a data storage device. A user selectable number of sequential data elements determines when previously used micro-cache memory locations will be overwritten.

Abstract: An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table in high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the reqested data record, the system directly accesses the requested data record on the storage medium thereby minimizing storage medium search time.

Abstract: Transceivers are selectively activated to reduce power in a network of data processing devices linked by a data transmission loop. Each of the devices is linked by a transceiver, and passes data from a previous device in the loop to a next device in the loop when not transmitting data onto the loop. For example, the data processing devices are disk drives in a storage subsystem. Delays in establishing communication after transceiver activation can be avoided by continuously powering a bit clock oscillator or bit synchronizer. In one embodiment, a loop controller in the loop sends activation and deactivation signals to addressed transceivers via an auxiliary channel. In another embodiment, when a device detects that communication is occurring between other devices for a certain period of time, the device selectively deactivates its transceiver for the certain period of time.

Abstract: Two data communication channels having electrical ground positions that alternate with control and data positions are terminated in a single, dual-channel connector that occupies generally the same interconnection board real estate as is required for a single, prior art, data communication SI connector, such as for a Small Computer System Interface (SCSI) communication channels. A two-channel SCSI connector system and connection method includes providing a two-channel header having two ground buses, to which the alternating electrical ground wires of respective first and second SCSI channels are terminated. Only a few of the pins or positions of the two-channel connector are connected to the two ground buses while the majority of pins or positions are connected to the signal (control, data) wires of the two SCSI channels.

Abstract: A dual bus architecture for a computer system including a number of computer system devices and a number of computer system resources. Each of the computer system devices and computer system resources are coupled by first and second communication busses. First and second bus arbitrators provide bus arbitration functions allowing first and second computer system devices to access first and second computer system resources simultaneously. A method of accessing a number of computer system resources by a number of computer system devices coupled by a dual bus architecture is also provided.

Abstract: An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table or high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the requested data record, the system directly accesses the requested data record on the storage medium thereby minimizing storage medium search time.

Abstract: A data storage system which automatically provides and maintains identical secondary data on a preferably geographically remote secondary data storage device. The system includes a primary host computer located in the first geographic location which is coupled to a primary data storage system also located in the first geographic location. The primary data storage system includes at least one primary data storage device on which primary data is to be stored, and a primary data storage system controller which receives data from the primary host computer and controls the storing of the primary data on the primary data storage device.

Abstract: A cache management system and method monitors and controls the contents of cache memory coupled to at least one host and at least one data storage device. A cache indexer maintains a current index of data elements which are stored in cache memory. A sequential data access indicator, responsive to the cache index and to a user selectable sequential data access threshold, determines that a sequential data access is in progress for a given process and provides an indication of the same. The system and method allocate a micro-cache memory to any process performing a sequential data access. In response to the indication of a sequential data access in progress and to a user selectable maximum number of data elements to be prefetched, a data retrieval requestor requests retrieval of up to the selected maximum number of data elements from a data storage device. A user selectable number of sequential data elements determines when previously used micro-cache memory locations will be overwritten.

Abstract: A data storage system with data mirroring and reduced access time data retrieval includes at least one pair of rotating data storage media each having a plurality of generally identical data records. Each rotating data storage medium includes position indicators, for providing one or more indications of the rotational position of each of the rotating data storage media with respect to its associated fixed position read/write mechanism. A position monitor receives the rotational position indications from each rotating data storage medium and computes and monitors the rotational position of each rotating storage medium with respect to its associated read/write mechanism.

Abstract: A cache management system and method monitors and controls the contents of cache memory coupled to at least one host and at least one data storage device. A cache indexer maintains a current index of data elements which are stored in cache memory. A sequential data access indicator, responsive to the cache index and to a user selectable sequential data access threshold, determines that a sequential data access is in progress for a given process and provides an indication of the same. The system and method allocate a micro-cache memory to any process performing a sequential data access. In response to the indication of a sequential data access in progress and to a user selectable maximum number of data elements to be prefetched, a data retrieval requestor requests retrieval of up to the selected maximum number of data elements from a data storage device. A user selectable number of sequential data elements determines when previously used micro-cache memory locations will be overwritten.

Abstract: A disk storage system including means for assuring completion of data writes to a data storage disk upon failure of electrical power receives data write commands including data to be written to one or more storage disks. Temporary memory storage temporarily stores the write commands including data to be written to one or more storage disks. The system generates a disk write pending indicator associated with each datum to be written to the one or more storage disks, for indicating that the data stored in the temporary memory must be written to disk. A disk director searches the temporary memory storage for data stored in the temporary memory storage that must be written to disk as indicated by the associated data write pending indicator, for writing the data to the one or more storage disks.

Abstract: A reconfigurable, multi-function data controller for use in a data storage system is selectively adaptable for use as a data channel adapter or a storage device adapter. The controller includes a data channel interface having at least one independent, bi-directional channel interface, for transmitting and receiving commands, data and status with one or more host computers. At least one memory interface transmits and receives commands and data to and from at least one high speed semiconductor memory unit. Additionally, a data storage interface controls and transmits data to and from one or more data storage devices such as a disk drive. A multi-function controller director is coupled to the data channel interface, the at least one memory interface, and the data storage device interface, for directing the reconfigurable multi-function data controller to function as either a data channel adapter or as a storage device adapter in response to selected commands received by the director.