Abstract: A data storage system has two computers. Each computer is assigned to a set of data. Two copies of each set of data are maintained. A first copy is stored on a first set of disks and a second copy is stored on a second set of disks. Each time that a data is written by a computer, a label is written to each set of disks, the label having fields for a status of each computer, a first ordinal which is increased each time that a new data is written, and a time stamp giving a time at which the last write was performed. After failure of a computer, a processor determines, in response to reading the labels of the first set of disks and the second set of disks, the most up to date copy of the data assigned to the failed computer.

Abstract: A method and system manages ownership information about disks in a storage network without the need for an emulated, partner mode system. The method and system provides for ownership information, including a current owner and a home owner for resources, such as disks, to be stored on each disk in a storage system, as well as to be stored in memory on each storage system node in the network. A further aspect of the invention is a disk homeness application program interface (API), which provides commands that can be utilized by an administrator at a host computer to set, modify and disco play ownership information about each disk in the cluster. Upon a takeover, any node in the network can takeover one or more disks by reading the ownership information stored on the disks or in the tables.

Abstract: A system and method for allowing more rapid takeover of a failed filer by a clustered takeover partner filer in the presence of a coredump procedure (e.g. a transfer of the failed filer's working memory) is provided. To save time, the coredump is allowed to occur contemporaneously with the takeover of the failed filer's regular, active file service disks by the partner so that the takeover need not await completion of the coredump to begin. This is accomplished, briefly stated, by the following techniques. The coredump is written to a single disk that is not involved in regular file service, so that takeover of regular file services can proceed without interference from coredump. A reliable means for both filers in a cluster to identify the coredump disk is provided, which removes takeover dependence upon unreliable communications mechanisms.

Abstract: A system and method for coordinated bringup of a storage appliance in a storage appliance cluster. The repaired storage appliance, during its initialization, sets a variety of state values in a predetermined memory location comprising a state data structure, which is detected by a remote direct memory access read operation by the surviving storage appliance. By the use of the RDMA operations, the repaired storage appliance and surviving storage appliance coordinate the bringup and giveback of data servicing functionality.

Abstract: This invention provides a system and method for selecting and communicating a single disk (a “coredump disk”) for use in a coredump procedure by a failed file server (or filer). A selection method on the failed filer determines the “best candidate” coredump disk according to a predetermined set of criteria. For example, the available disks that can receive coredump data are located and ordered so as to prefer disks that best match the coredump data size requirement, are least likely to be needed for normal service by the server; and require the least preparation to receive coredump data. Appropriate attributes on the selected coredump disk are written to indicate that a coredump is in progress, and the location of the coredump data. Upon reboot of the failed filer (or takeover by a cluster partner), the coredump disk is identified and the coredump data recovered by reading back appropriate attributes.

Abstract: A computer server system and a method for operating the system are described. An address and a status of each computer device of a plurality of computer devices accessible to a switch is written into a memory in the switch. The status of a first computer device which is off line is set to indicate that the first computer device is off line. The status information is read from the memory in the switch by a second computer device so that the second computer device knows that the first computer device is off line. Embodiments are described where the status of a data storage device and the status of a server are written to the memory in the switch.

Abstract: A multiple node storage system cluster that allows for a takeover by a takeover node simultaneously with a failing node resetting its storage adapters is provided. A takeover monitor on the failing node initiates a “coredump” procedure by selecting a coredump disk. After selecting the coredump disk, the failing node determines the world wide name (WWN) of that disk and sends this information in a message across the cluster interconnect to the takeover node. In response to receipt of this message, the takeover node begins takeover procedures with respect to all disks except for the coredump disk. The failing node simultaneously resets its storage adapters and writes is memory to the coredump disk. The failing node later updates a completion header on that disk. The takeover node completes the takeover without waiting for the storage adapter reset, and subsequently reads the completion header and copies coredump information into its memory.

Abstract: A system and method for performing a takeover procedure is disclosed. A plurality of storage system nodes is coupled in a cluster. One or more of the plurality of storage system nodes in the cluster is notified to takeover at least a portion of a writable storage device serviced by another storage system node in the cluster. In response to the notification, the portion of the writable storage device is assimilated into at least one of the notified storage system nodes.

Abstract: An apparatus and a method that prevent a split-brain problem by preventing a cluster partner from accessing and serving data when the cluster partner is taken over by a storage server, while allowing early release of reservations on the cluster partner's storage devices before control is given back to the cluster partner.

Abstract: A system and method for allowing more rapid takeover of a failed filer by a clustered takeover partner filer in the presence of a coredump procedure (e.g. a transfer of the failed filer's working memory) is provided. To save time, the coredump is allowed to occur contemporaneously with the takeover of the failed filer's regular, active file service disks by the partner so that the takeover need not await completion of the coredump to begin. This is accomplished, briefly stated, by the following techniques. The coredump is written to a single disk that is not involved in regular file service, so that takeover of regular file services can proceed without interference from coredump. A reliable means for both filers in a cluster to identify the coredump disk is provided, which removes takeover dependence upon unreliable communications mechanisms.

Abstract: A cluster comprises a plurality of nodes that access a shared storage, each node having two or more partner nodes. A primary node may own a plurality of aggregate sub-sets in the shared storage. Upon failure of the primary node, each partner node may take over ownership of an aggregate sub-set according to an aggregate failover data structure (AFDS). The AFDS may specify, an ordered data structure of two or more partner nodes to take over each aggregate sub-set, the ordered data structure comprising at least a first-ordered partner node assigned to take over the aggregate sub-set upon failure of the primary node and a second-ordered partner node assigned to take over the aggregate sub-set upon failure of the primary node and the first-ordered partner node. The additional workload of the failed primary node is distributed among two or more partner nodes and protection for multiple node failures is provided.

Abstract: In a method for operating a data storage system, a request is issued that an ownership attribute of a logical arrangement of storage space associated with a first storage system be associated with a second storage system. In response to the request, the ownership attribute is changed to a state of unowned. In response to the request, and in response to the state of unowned, the ownership attribute of the logical arrangement of storage space is changed to a new set of attributes associated with the second storage system to change ownership of the logical arrangement of storage space from the first storage system to the second storage system.

Abstract: A system and method for determining a disk ownership model to be utilized by a storage system is disclosed. The storage system and method determines the individual disk ownership of each accessible disk to the storage system. If the number of disks utilizing a first ownership model is exceeded, the storage system utilizes the first ownership model. Otherwise, the storage system utilizes a second ownership model.

Abstract: A method and system manages ownership information about disks in a storage network without the need for an emulated, partner mode system. The method and system provides for ownership information, including a current owner and a home owner for resources, such as disks, to be stored on each disk in a storage system, as well as to be stored in memory on each storage system node in the network. A further aspect of the invention is a disk homeness application program interface (API), which provides commands that can be utilized by an administrator at a host computer to set, modify and display ownership information about each disk in the cluster. Upon a takeover, any node in the network can takeover one or more disks by reading the ownership information stored on the disks or in the tables.

Abstract: A system and method for disk ownership in a network storage system. Each disk has two ownership attributes set to show that a particular file server owns the disk. In a preferred embodiment the first ownership attribute is the serial number of the file server being written to a specific location on each disk and the second ownership attribute is setting a SCSI-3 persistent reservation. In a system utilizing this disk ownership method, multiple file servers can read data from a given disk, but only the file server that owns a particular disk can write data to the disk.

Abstract: A takeover system and method for high availability in the face of component failures for a multiple-node storage system cluster is provided. When a takeover is triggered either through a loss of cluster heartbeat, or through a user-initiated command, the system of the present invention is configured such that one or more surviving nodes asserts ownership on one or more of the failed node's disks such that all of the disks become locally owned by one of the surviving nodes. An assimilation of the disks into one or more aggregates is performed, and any duplicated file system identification numbers are corrected to avoid errors. As the disks thus appear to be locally owned by the surviving nodes, one or more newly assimilated aggregates are thus exposed to any N-module that interfaces with the surviving nodes.

Abstract: A method and system performs a sendhome procedure for giving back resources to a node that had been restored after a takeover of that node's resources is provided. Critical operations that may be running are completed prior to the sendhome process. An ownership module consults information in an ownership table about each resource, e.g. a data container. A data container, such as a root aggregate of the waiting node is identified and sent back first, after which the node is booted. When the node has been successfully booted, the remaining aggregates are sent back one at a time until the full compliment of aggregates has been returned. A veto of the sendhome procedure can be invoked by a subsystem that is performing a critical operation prior to the sendhome of the root aggregate and each individual other aggregate.

Abstract: A storage system includes a plurality of mass storage devices and a first storage server head to access the mass storage devices in response to client requests, wherein the first storage server head has ownership of the plurality of mass storage devices. Ownership of at least one of the mass storage devices is reassigned to a second storage server head independently of how the second storage server head is connected to the plurality of mass storage devices.

Abstract: The present invention includes a processing system. The processing system includes a controller to manage the processing system. The processing system also includes a remote management module coupled to said controller and a network. The remote management module to monitor operating conditions of said controller and to send a message on said network responsive to operating conditions that indicate a failure of said controller to a failover partner.

Abstract: A data storage system has two computers. Each computer is assigned to a set of data. Two copies of each set of data are maintained. A first copy is stored on a first set of disks and a second copy is stored on a second set of disks. Each time that a data is written by a computer, a label is written to each set of disks, the label having fields for a status of each computer, a first ordinal which is increased each time that a new data is written, and a time stamp giving a time at which the last write was performed. After failure of a computer, a processor determines, in response to reading the labels of the first set of disks and the second set of disks, the most up to date copy of the data assigned to the failed computer.