摘要:
In a disk mass storage facility for data processing systems, a disk format which improves handling of defective segments of medium and reduces access time. The format has three layers. A first, physical layer comprises the bytes, sectors and collections of sectors, as well as error detection and correction codes. A second, logical layer is used to address the physical layer and to collect together sectors to form a multiplicity of separately addressable spaces, with each space having a distinct functional utility. At a third, functional layer the use of data fields in each space is specified. This layer governs the handling of bad blocks if required, and the use of certain format information. Handling of bad blocks is controlled by a hierarchically layered process. A portion of each disc, distributed across the medium, is reserved as spare sectors to replace defective sectors. After a bad sector is replaced, future attempts to access the bad sector are redirected (i.e., revectored) to the replacement sector. For the simplest revectoring, the bad block is replaced by a replacement block in a known location. If that cannot be done, multiple copies of the replacement block's header are stored in the bad block's data field and the copies are compared to find the replacement address. If the comparison fails, or the header cannot be read, a back-up table is available to match the available replacement addresses with the original address which was replaced. A special code is used to identify blocks wherein the medium is good but the contents of the block are logically corrupted.
摘要:
A control arrangement for coordinating operations of multiple processors in a multiprocessor system in response to a command. Each command is associated with a route comprising a sequence of route vectors, each identifying an operation to be performed to execute the command, as well as the process, or station, to execute the route vector. In response to the receipt of a command, a control block is generated identifying the first route vector in the route associated with the command. Each station has a work queue containing control blocks, which the station retrieves and processes sequentially. The control block is first sent to the work queue of the station to perform the first operation. When the station gets to the control block, it performs the operation required by the route vector, modifies the control block to identify the next route vector in the sequence, and transfers the control block to the work queue of the station to perform the operation required by the next route vector in the route.
摘要:
An interface mechanism (10) between two processors, such as a host processor (70) and a processor (31) in an intelligent controller (30) for mass storage devices (40), and utilizing a set of data structures employing a dedicated communications region (80A) in host memory (80). Interprocessor commands and responses are communicated as packets over an I/O bus (60) of the host (70), to and from the communication region (80A), through a pair of ring-type queues (80D) and (80E). The entry of each ring location (e.g., 132, 134, 136, 138) points to another location in the communications region where a command or response is placed. The filling and emptying of ring entries (132-138) is controlled through the use of an `ownership` byte or bit (278) associated with each entry. The ownership bit (278) is placed in a first state when the message source (70 or 31) has filled the entry and in a second state when the entry has been emptied. Each processor keeps track of the rings' status, to prevent the sending of more messages than the rings can hold. These rings permit each processor to operate at its own speed, without creating race conditions and obviate the need for hardware interlock capability on the I/O bus (60).
摘要:
The present invention provides a virtual storage system that generally stores uses larger segmentations, but divides large segments into smaller sub-segments during data movement operations. The present invention provides a method and system having this hierarchy of segment sizes, namely a large segment for the normal case, while breaking the large segment into single disk blocks during data movement. The mapping has large segments except for those segments undergoing data movement. For those segments, it would be desirable to have the smallest segment size possible, namely, a single disk block. In this way, the administration costs are generally low, but latencies caused by the movement of large data blocks are avoided.
摘要:
A digital data processing system with a central processor for responding to diverse instructions including instructions for calling subroutines. When the central processor executes a calling instruction, the central processor saves information corresponding to the operating environment for the calling routine and then utilizes corresponding information in the subroutine to establish the operating environment for the subroutine. A common return instruction at the completion of each subroutine causes the central processor to retrieve the saved operating information thereby to reestablish the operating environment for the calling routine.
摘要:
A disaster-tolerant data backup and remote copy system which is implemented as a controller-based replication of one or more LUNs (logical units) between two remotely separated pairs of array controllers connected by redundant links. The system provides a method for allowing a large number of commands to be ‘outstanding’ in transit between local and remote sites while ensuring the proper ordering of commands on remote media during asynchronous or synchronous data replication. In addition, the system provides a mechanism for automatic ‘tuning’ of links based on the distance between the array controllers.
摘要:
A data replication system having a redundant configuration including dual Fibre Channel fabric links interconnecting each of the components of two data storage sites, wherein each site comprises a host computer and associated data storage array, with redundant array controllers and adapters. Each array controller in the system is capable of performing all of the data replication functions, and each host ‘sees’ remote data as if it were local. Each array controller has a dedicated link via a fabric to a partner on the remote side of the long-distance link between fabric elements. Each dedicated link does not appear to any host as an available link to them for data access; however, it is visible to the partner array controllers involved in data replication operations. These links are managed by each partner array controller as if being ‘clustered’ with a reliable data link between them.
摘要:
A system and technique for optimizing the efficiency of maintenance operations performed on skip lists of data elements or nodes stored in memory is provided. Each node of a skip list includes a back pointer for pointing to an immediate predecessor node and a node level field for recording the node level associated with the node. The system further includes a system agent for operating on the data structure, the system agent capable of locating the address of the immediate predecessor node pointing to a selected node by using the back pointer in the selected node.
摘要:
A pipelined multi-staged logic control device for controlling the movement of information between a number of storage devices and a host computer. The pipelined multi-staged logic control device resides in a controller having a first and a second data bus wherein each of the data buses can access up to four drive ports. Information can flow through either of the data buses to any one of the eight total drive ports. A pair of indentical integrated circuit chips are each coupled individually to a single state machine. Each of the integrated circuit chips act in concert with their associated state machine to examine the state of the drive ports and to decide if a requested drive port can be accessed. The present invention is extremely fast due to the use of state machines. While a pickup head is locating information on a storage device, other requests for information are checked during this time to determine whether additional requests can be satisfied during the pickup head's locate time.
摘要:
An address conversion unit for a multiprocessor system including a common memory, and in which at least one processor includes a private memory, with the private memory and common memory having separate and distinct memory spaces. The conversion unit converts addresses between private addresses that are used within the processor itself and addresses that are used to retrieve contents of locations in common memory.