摘要:
Apparatus for assigning addresses to devices connected to a small computer system interface (SCSI) bus. A second configure bus interconnects address assignable devices on the SCSI bus. The assignable devices may be used in a mixed system where some devices have fixed non-assignable addresses. The master device in the SCSI bus transmits configuration commands over the configuration bus and addresses for assignment over the SCSI bus. Acknowledgements are received back from a device which has accepted an address. Once configured with an address, the device propagates subsequent configuration commands to an adjacent device.
摘要:
When transferring data to a cache memory from an attachment data storage device, additional unrequested information can be transferred at the same time if it is likely that this additional data will soon be requested. The average quantity of data transferred to the cache memory in each operation can be automatically and continually varied in order to maximize the performance advantage provided by the cache memory. When a record of data is requested by the host processor, data is transferred to the cache memory from an attachment data storage device in increments of fixed-length data blocks each containing a sequence of data records, with the number of transferred blocks being determined by the position of a requested data record in its respective data block, and the average number of blocks transferred in any one operation being varied by adjusting threshold position values at which second or third data blocks are transferred.
摘要:
Arrangements for physically partitioning a bus having a well defined architecture as a physical entity, wherein the partitioning is logically transparent to a computer and devices which communicate through the bus and serves to avoid problems potentially arising because of the scope of actions permitted by the architecture. A typical bus architecture to which present arrangements have relevance is that associated with SCSI (Small Computer System Interface) buses. The potential problems allowed to occur architecturally involve: (a) exposures of data security/integrity; (b) excessive signal degradation due to use of signal rates which although allowed by the architecture are inappropriate for a particular bus loading environment also allowed by the architecture; (c) restrictions preventing parallel transfer of data between the computer and multiple storage devices; (d) restrictions unduly limiting the number of devices attachable to one logical bus path (one input-output channel of the computer). The disclosed arrangement partitions the bus into two or more physical entities which to the computer appears as one logical entity.
摘要:
A plug-in feature board for a computer system has special circuitry to permit the board to customize itself to the particular slot into which it is inserted. Computers of the type intended for individual use or use in small networks typically provide insertion slots including connectors to permit feature boards to be added and connected to a bus of the computer for adding new function or capacity. As the computing power of such systems has increased there have been increases in the size of portions of the connecting bus to permit improvements in data transfer performance. In a given computer system there are often two or more bus connector configurations presented in respective slots. By so converting electrical states at selected connector positions as to provide signal information for determining bus configuration for the slot, special logic provided on the board is enabled to determine the characteristics of the slot in which the board is placed and customizes the board to respond or limit response in accordance with the requirements for that configuration. By so adapting to the slot the board achieves enhanced applicability and avoids certain system disabling malfunctions which can occur when a board is plugged into a slot for which it is not configured.
摘要:
On board diagnostic capability for a SCSI controller is provided within an adapter by providing a gate array driven by a microprocessor on board the adapter. The gate array has data and control inputs driven from the microprocessor and data and control outputs which are dot OR'ed with corresponding in/out terminals of the SCSI controller. A reset signal from a SCSI bus forms a further input to the gate array. For testing purposes the microprocessor drives the gate array inputs to simulate a fault-free or faulty device. The microprocessor detects the response of the SCSI controller to the device simulation and thereby can determine the state of health of the SCSI controller.
摘要:
Apparatus and method for increasing efficiency of command execution from a host processor over an SCSI bus. Arbitration, selection and message out functions of SCSI protocol are implemented using a background arbitration state machine. Additional protocol functions are implemented in a foreground state machine. When the host processor issues a command for access to the SCSI bus, the background state machine can be programmed before the foreground machine completes the protocol function for a previous command. Thus, the background state machine is ready to arbitrate for access to the bus at the very next bus free condition.
摘要:
A storage subsystem such as an array of disk drives, method of managing disk drives in the storage subsystem and program product therefor. The storage subsystem may be a redundant array of independent disks (RAID) and the individual disks drives may be Self-Monitoring, Analysis and Reporting Technology (SMART) capable drives. When one of the drives gives an indication of an impending failure, a disk image of the failing disk is built on an available spare disk. Once the image is complete, the failing disk may be replaced without down time for rebuilding a failed disk.
摘要:
An apparatus and method for protecting BIOS stored on a direct access storage device into a personnal computer system. The personal computer system comprises a system processor, a system planar, a random access main memory, a read only memory, a protection means and at least one direct access storage device. The read only memory includes a first portion of BIOS and data representing the type of system processor and system planar I/O configuration. The first portion of BIOS initializes the system and the direct access storage device, and resets the protection means in order to read in a master boot record into the random access memory from a protectable partition on the direct access storage device.
摘要:
A storage subsystem such as an array of disk drives, method of managing disk drives in the storage subsystem and program product therefor. The storage subsystem may be a redundant array of independent disks (RAID) and the individual disks drives may be Self-Monitoring, Analysis and Reporting Technology (SMART) capable drives. When one of the drives gives an indication of an impending failure, a disk image of the failing disk is built on an available spare disk. Once the image is complete, the failing disk may be replaced without down time for rebuilding a failed disk.
摘要:
A Command interface includes ports for transferring information between a host processor and at least one intelligent subsystem which may have attached devices. A Command Interface port receives either a direct command or an indirect command from the host processor, which commands are indicative of a type of operation to be performed by the one subsystem or an attached device. An Attention port receives a code from the host processor which is indicative of which one of the direct command or the indirect command is received at the Command Interface port, and which is also indicative of which of the one intelligent subsystem or a device is to execute the command. A command busy/status port receives a code from the one intelligent subsystem which is indicative of whether or not the Command Interface port and the Attention port are busy, and whether or not the one intelligent subsystem is accepting or rejecting commands. The host processor can read this port without altering or updating the code.