Abstract: A data storage system is disclosed in which a 3-party hand-off protocol is utilized to maintain a single coherent logical image. In particular, the functionality of the data storage system is separated into distinct processing modules. Each processing module is implemented in a distinct central processing unit (CPU). Alternatively, the first type processing module and the third type processing module can be implemented in a common CPU. Isolating the different functions of the data storage system into distinct CPUs facilitates failure recovery. A characteristic of the 3-party hand-off protocol is that, if an abnormal state occurs, a surviving module has sufficient information to proceed to recover from said abnormal state after detecting the abnormal state, without depending on a failing module, by retrying the data storage operation with another processing module or the failing module or cleaning up after the failed data storage operation, resulting in improved failure recovery.

Abstract: A memory system is disclosed in which hardware assisted leases are utilized to control access to shared data resources among data users. The lease is a type of lock on content in the memory system that automatically expires after a preset period of time. The lease enables the lease owner exclusive use of the associated content in the memory system. Furthermore, the memory system has a memory access mechanism that is separate from the data users. The memory access mechanism includes hardware components to enforce lease-based access to the memory system. Since the lease expires rather than being permanently granted, no CPU or software thread is able to monopolize a lease forever. Moreover, since the lease-base access is hardware-assisted, faulty CPUs or software are prevented from unauthorized access to leased (or locked) content in which another CPU or software already holds a lease.

Abstract: A data storage system is disclosed in which a 3-party hand-off protocol is utilized to maintain a single coherent logical image. In particular, the functionality of the data storage system is separated into distinct processing modules. There are at least three types of processing modules. These three kinds of processing modules function cooperatively to perform data storage operations via the 3-party hand-off protocol. At least two types of processing modules are required to cooperate in a hand-off manner to fully execute each data storage operation.

Abstract: A system and related method are described for booting from one of multiple boot images that includes a processor coupled to a main memory, a number of boot devices and a selector. The boot devices are used to store multiple copies of a boot image and are in communication with the processor through a controller. The selector is used to select a different boot device each time the system is turned on or reset. A set of instructions executed by the processor loads the boot image from one of the boot devices selected by the selector into the main memory. In one embodiment, the selector is embodied in the form of software instructions incorporated into or linked to a system BIOS program. In another embodiment, the selector is embodied in the form of software instructions incorporated into or linked to a SCSI BIOS program.

Abstract: A fault tolerant data storage system and related method are described for effectively failing over a storage device from one storage controller to another storage controller. The storage system generally includes at least two storage controllers for coupling to a processor and at least one storage device. A failover manager is in communication with the storage controllers and the storage device. The failover manager assists failing over of the storage device by allowing only one of the storage controllers having ownership to access the storage device at any one time. In one embodiment, the failover manager maintains a list of recent requests that have been committed to the storage device so that it can be used during failover to assist the surviving controller to complete the uncommitted requests properly.

Abstract: A data layout mechanism is described for allocating metadata within a storage system employing data striping. The data layout mechanism includes a number of storage devices, each of the storage devices having storage spaces allocated to store individual data stripe units associated with a number of stripes. The data layout mechanism further includes a plurality of metadata chunks allocated within the storage devices such that (1) metadata associated with at least two data stripe units of the same stripe is stored within a single metadata chunk, and (2) the metadata chunks are evenly distributed across the storage devices.

Abstract: A data storage system is disclosed in which a 3-party hand-off protocol is utilized to maintain a single coherent logical image. In particular, the functionality of the data storage system is separated into distinct processing modules. There are at least three types of processing modules. These three kinds of processing modules function cooperatively to perform data storage operations via the 3-party hand-off protocol. At least two types of processing modules are required to cooperate in a hand-off manner to fully execute each data storage operation.

Abstract: A data storage system is disclosed in which a 3-party hand-off protocol is utilized to maintain a single coherent logical image. In particular, the functionality of the data storage system is separated into distinct processing modules. Each processing module is implemented in a distinct central processing unit (CPU). Alternatively, the first type processing module and the third type processing module can be implemented in a common CPU. Isolating the different functions of the data storage system into distinct CPUs facilitates failure recovery. A characteristic of the 3-party hand-off protocol is that, if an abnormal state occurs, a surviving module has sufficient information to proceed to recover from said abnormal state after detecting the abnormal state, without depending on a failing module, by retrying the data storage operation with another processing module or the failing module or cleaning up after the failed data storage operation, resulting in improved failure recovery.

Abstract: A memory system is disclosed in which hardware assisted leases are utilized to control access to shared data resources among data users. The lease is a type of lock on content in the memory system that automatically expires after a preset period of time. The lease enables the lease owner exclusive use of the associated content in the memory system. Furthermore, the memory system has a memory access mechanism that is separate from the data users. The memory access mechanism includes hardware components to enforce lease-based access to the memory system. Since the lease expires rather than being permanently granted, no CPU or software thread is able to monopolize a lease forever. Moreover, since the lease-base access is hardware-assisted, faulty CPUs or software are prevented from unauthorized access to leased (or locked) content in which another CPU or software already holds a lease.

Abstract: A network and storage I/O device is described for use with a host computer system having a system bus coupled to a host processor and a main memory to provide a high bandwidth network server system. The network and storage I/O device includes a plurality of network controllers to communicate with client computers connected over a network, a plurality of storage controllers to transfer data to and from storage devices, at least one memory element to temporarily store data transferred between the network controllers and the storage controllers and a crossbar switch having a plurality of nodes to interconnect the plurality of network controllers, the plurality of storage controllers and the at least one memory element. The network and storage I/O device also includes a bridge coupled between one of the nodes and the system bus of the host computer.

Abstract: Systems and methods for routing messages in an interconnection fabric are provided. The fabric includes a plurality of nodes, each node having, for example, four ports coupled to adjacent nodes in the fabric. A source node initiating a message in the fabric can transmit the message out of one of its four ports. Between a source node and a destination node, there are at least four independent paths which may be taken, depending on the output port from the source node. However, the precise path is not expressly delineated in the message. Instead, the message contains the address of the destination node, the address of the originating node, and a target region for the message. Each intermediate node is configured to receive a message via one of its four ports, and then select an appropriate output port based on the location of the port which received the message combined with the address and target information contained in the message.

Abstract: A substrate for packaging a storage or server system may include one or more sections of the substrate configured to hold a two-dimensional array of disk drives. Another section of this substrate may be configured to hold circuitry for accessing the array of disk drives. This circuitry may include one or more processors. The substrate also includes a first plurality of ribs positioned in the first access of the substrate. The first plurality of ribs separate the sections from one another. The section configured to hold the control circuitry may also be configured to hold one or more power supplies for supplying power to the array of disk drives and control circuitry. This section, as well as other sections, may be divided in two by one or more additional ribs in a transverse direction. The substrate may be configured to be mounted in a cage or rack and may include an edge connector at one edge of the substrate to provide electrical connectivity to a back plane in the cage or rack.

Abstract: A substrate for packaging a storage or server system may include one or more sections of the substrate configured to hold a two-dimensional array of disk drives. Another section of this substrate may be configured to hold circuitry for accessing the array of disk drives. This circuitry may include one or more processors. The substrate also includes a first plurality of ribs positioned in the first access of the substrate. The first plurality of ribs separate the sections from one another. The section configured to hold the control circuitry may also be configured to hold one or more power supplies for supplying power to the array of disk drives and control circuitry. This section, as well as other sections, may be divided in two by one or more additional ribs in a transverse direction. The substrate may be configured to be mounted in a cage or rack and may include an edge connector at one edge of the substrate to provide electrical connectivity to a back plane in the cage or rack.