Abstract: An Input/Output (I/O) adapter for use with a second I/O adapter in a clustered configuration. The I/O adapter includes a dedicated communication link, such as a high-speed serial bus, that provides for communication between the I/O adapter and the second I/O adapter. The I/O adapter also includes a message passing circuit, coupled to the dedicated communication link, that allows for transferring of data between the I/O adapter and the second I/O adapter. The I/O adapter further includes a doorbell circuit, coupled to the message passing circuit, that generates interrupts to provide a low level communication between the I/O adapter and the second I/O adapter. A mirroring directory, coupled to the message passing circuit, is also included in the I/O adapter to provide for the mirroring of cache directory writes.

Abstract: A redundancy manager preferably in an I/O adapter has been disclosed to manage commands to peripheral devices in a computer system. These peripheral devices have multiple ports and may have a different bus associated with each port. The buses, referred to as independent pathways, moreover, need not have the same protocol. The redundancy manager determines the number of independent pathways connected to the peripheral device, presents only one logical device to the operating system and any device driver and any other command or device processing logic in the command path before the redundancy manager. For each incoming command, the redundancy manager determines which pathways are properly functioning and selects the best pathway for the command based on load balancing considerations and any ordering semantics that must be preserved in the incoming command and any outstanding commands and associated data that have not yet executed.

Abstract: A storage area network (SAN) fibre channel arbitrated loop (FCAL) multiple system, multiple resource, storage enclosure and a method are provided for performing enclosure maintenance concurrent with device operations. The storage enclosure includes a plurality of storage resources or storage devices, a plurality of IO adapters (IOAs) coupled to the storage area network and a pair of enclosure services node cards. Each enclosure services node card includes loop connections for the plurality of storage resources. Each enclosure services node card includes a respective global bus connection and a loop connection to each of the plurality of IOAs. Each enclosure services node card is used concurrently by the multiple systems to manage the plurality of storage resources. In the method for performing enclosure maintenance concurrent with device operations, identical maintenance procedures are implemented for the enclosure services node cards and the storage devices.

Abstract: A method for maintaining data coherency in a dual Input/Output(I/O) adapter having primary and secondary adapters, wherein each of the primary and secondary adapters includes resident write cache data and directory storage devices. The method includes utilizing a split point to separate each of the cache data and directory storage devices into first and second regions, wherein the first regions contain the primary adapter cache data and directory information and the second regions contain the secondary adapter cache data and directory information. Information stored in the primary adapter cache data and directory storage devices is mirrored into the secondary adapter cache data and directory storage devices or, alternatively, information stored in the secondary adapter cache data and directory storage devices is mirrored into the primary adapter cache data and directory storage devices utilizing a dedicated communication link, such as a high-speed serial bus, between the primary and secondary adapters.

Abstract: A method for maintaining data coherency in a dual Input/Output(I/O) adapter having primary and secondary adapters, wherein each of the primary and secondary adapters includes resident write cache data and directory storage devices. The method includes utilizing a split point to separate each of the cache data and directory storage devices into first and second regions, wherein the first regions contain the primary adapter cache data and directory information and the second regions contain the secondary adapter cache data and directory information. Information stored in the primary adapter cache data and directory storage devices is mirrored into the secondary adapter cache data and directory storage devices or, alternatively, information stored in the secondary adapter cache data and directory storage devices is mirrored into the primary adapter cache data and directory storage devices utilizing a dedicated communication link, such as a high-speed serial bus, between the primary and secondary adapters.

Abstract: An Input/Output (I/O) adapter for use with a second I/O adapter in a clustered configuration. The I/O adapter includes a dedicated communication link, such as a high-speed serial bus, that provides for communication between the I/O adapter and the second I/O adapter. The I/O adapter also includes a message passing circuit, coupled to the dedicated communication link, that allows for transferring of data between the I/O adapter and the second I/O adapter. The I/O adapter further includes a doorbell circuit, coupled to the message passing circuit, that generates interrupts to provide a low level communication between the I/O adapter and the second I/O adapter. A mirroring directory, coupled to the message passing circuit, is also included in the I/O adapter to provide for the mirroring of cache directory writes.

Abstract: A storage area network (SAN) fibre channel arbitrated loop (FCAL) multiple system, multiple resource, storage enclosure and a method are provided for performing enclosure maintenance concurrent with device operations. The storage enclosure includes a plurality of storage resources or storage devices, a plurality of IO adapters (IOAs) coupled to the storage area network and a pair of enclosure services node cards. Each enclosure services node card includes loop connections for the plurality of storage resources. Each enclosure services node card includes a respective global bus connection and a loop connection to each of the plurality of IOAs. Each enclosure services node card is used concurrently by the multiple systems to manage the plurality of storage resources. In the method for performing enclosure maintenance concurrent with device operations, identical maintenance procedures are implemented for the enclosure services node cards and the storage devices.

Abstract: A redundancy manager preferably in an I/O adapter has been disclosed to manage commands to peripheral devices in a computer system. These peripheral devices have multiple ports and may have a different bus associated with each port. The buses, referred to as independent pathways, moreover, need not have the same protocol. The redundancy manager determines the number of independent pathways connected to the peripheral device, presents only one logical device to the operating system and any device driver and any other command or device processing logic in the command path before the redundancy manager. For each incoming command, the redundancy manager determines which pathways are properly functioning and selects the best pathway for the command based on load balancing considerations and any ordering semantics that must be preserved in the incoming command and any outstanding commands and associated data that have not yet executed.

Abstract: A method and apparatus are provided for adaptive localization of frequently accessed, randomly addressed data in a direct access storage device (DASD) to achieve improved system access performance. At selected sampling intervals, a DASD storage controller analyzes data access patterns based on frequency of access, identifies a remapping algorithm to remap the logical groups to physical groups, and moves the physical groups according to the identified remapping algorithm. The data reordering on the DASD provides frequently accessed data in close proximity so that seek time is minimized. The adaptive data localization method periodically performed by the storage controller is transparent to the host file system. The reordering of the data on the DASD is performed during periods of low system data transfer activity.

Abstract: Problem ownership and status propagation in a clustered system environment must be coordinated in a way that avoids redundant and/or conflicting recovery efforts. IOP managers which overcome these problems are disclosed. A primary IOP manager is one which has problem ownership for a particular IOP. There is only one primary IOP manager for each IOP. A secondary IOP manager is one which resides upon a computer system that shares the resources of a particular IOP or IOPs, but nevertheless does not have problem ownership for that particular IOP(s). There are one or more secondary IOP managers for a given IOP. When a primary IOP manager is informed of a problem in a device attached to a shared IOP, it updates resident system management information to indicate the new status of the subject device, informs its local system management of the problem so that corrective actions may be taken, and sends the status information to the secondary IOP managers via the IOP itself.