Abstract: A system is provided. The system includes a storage controller configured to receive a prefetch command from a host interface. The storage controller includes a read cache memory that stores prefetch data in response to the prefetch command and a plurality of storage tiers coupled to the storage controller and providing the prefetch data. The plurality of storage tiers includes a fastest storage tier that stores the prefetch data if the read cache memory discards the prefetch data after storing the prefetch data.

Abstract: A system is provided. The system includes a storage controller configured to receive a prefetch command from a host interface. The storage controller includes a read cache memory that stores prefetch data in response to the prefetch command and a plurality of storage tiers coupled to the storage controller and providing the prefetch data. The plurality of storage tiers includes a fastest storage tier that stores the prefetch data if the read cache memory discards the prefetch data after storing the prefetch data.

Abstract: A plurality of arrays of storage devices, each providing dual storage device redundancy, is provided. The plurality of arrays of storage devices includes a plurality of mirrored sets of primary storage devices, each including an even number of at least two or more primary storage devices. Each of the mirrored sets of primary storage devices stores a first and a second copy of data. The plurality of arrays of storage devices also includes a secondary storage device, which is a single physical storage device that stores a third copy of the data stored on each of the plurality of mirrored sets of primary storage devices. The secondary storage device has at least the capacity to store the data stored on the plurality of mirrored sets of primary storage devices. Dual storage device redundancy preserves data if data cannot be read from one or two physical storage devices in any array.

Abstract: A rackmountable storage enclosure includes a chassis. The chassis includes one or more power supplies and a plurality of drawers, each extendable through a front surface of the chassis. Each drawer of the plurality of drawers provides mounting for one or more storage devices. All storage devices in any drawer of the plurality of drawers are inserted or removed through a common side of the drawer. Any storage device may be inserted or removed from any drawer of the plurality of drawers even if the side surfaces of the chassis are each parallel to and in contact with a wall, each of the walls extending forward at least to a fully extended length of any drawer. Electrical failures in any one drawer are prevented from affecting any other drawer of the plurality of drawers. The one or more power supplies provides DC power to the plurality of drawers.

Abstract: A network storage appliance is disclosed. The storage appliance includes a port combiner that provides data communication between at least first, second, and third I/O ports; a storage controller that controls storage devices and includes the first I/O port; a server having the second I/O port; and an I/O connector for networking the third I/O port to the port combiner. A single chassis encloses the port combiner, storage controller, and server, and the I/O connector is affixed on the storage appliance. The third I/O port is external to the chassis and is not enclosed therein. In various embodiments, the port combiner comprises a FiberChannel hub comprising a series of loop resiliency circuits, or a FiberChannel, Ethernet, or Infiniband switch. In one embodiment, the port combiner, I/O ports, and server are all comprised in a single blade module for plugging into a backplane of the chassis.

Abstract: A plurality of arrays of storage devices, each providing dual storage device redundancy, is provided. The plurality of arrays of storage devices includes a plurality of mirrored sets of primary storage devices, each including an even number of at least two or more primary storage devices. Each of the mirrored sets of primary storage devices stores a first and a second copy of data. The plurality of arrays of storage devices also includes a secondary storage device, which is a single physical storage device that stores a third copy of the data stored on each of the plurality of mirrored sets of primary storage devices. The secondary storage device has at least the capacity to store the data stored on the plurality of mirrored sets of primary storage devices. Dual storage device redundancy preserves data if data cannot be read from one or two physical storage devices in any array.

Abstract: A rackmountable storage enclosure includes a chassis. The chassis includes one or more power supplies and a plurality of drawers, each extendable through a front surface of the chassis. Each drawer of the plurality of drawers provides mounting for one or more storage devices. All storage devices in any drawer of the plurality of drawers are inserted or removed through a common side of the drawer. Any storage device may be inserted or removed from any drawer of the plurality of drawers even if the side surfaces of the chassis are each parallel to and in contact with a wall, each of the walls extending forward at least to a fully extended length of any drawer. Electrical failures in any one drawer are prevented from affecting any other drawer of the plurality of drawers. The one or more power supplies provides DC power to the plurality of drawers.

Abstract: A network storage appliance is disclosed. The appliance includes a chassis enclosing a backplane, and a server enclosed in the chassis and coupled to the backplane. The appliance also includes storage controllers enclosed in the chassis, each coupled to the backplane, which control transfer of data between the server and storage devices coupled to the storage controllers. The storage controllers also control transfer of data between the storage devices and computers networked to the appliance and external to the appliance. The storage controllers and the server comprise a plurality of hot-replaceable blades. Any one of the plurality of blades may be replaced during operation of the appliance without loss of access to the storage devices by the computers. In one embodiment, the server executes storage application software, such as backup software for backing up data on the storage devices, such as to a tape device networked to the server.

Abstract: A storage system includes two RAID controllers, each having two SAS initiators coupled to a zoning SAS expander. The expanders are linked by an inter-controller link and create a SAS ZPSDS. The expanders have PHY-to-zone mappings and zone permissions to create two distinct SAS domains such that one initiator of each RAID controller is in one domain and the other initiator is in the other domain. The disk drives are dual-ported, and each port of each drive is in a different domain. Each initiator can access every drive in the system, half directly through the local expander and half indirectly through the other RAID controller's expander via the inter-controller link. Thus, a RAID controller can continue to access a drive via the remote path in the remote domain if the drive becomes inaccessible via the local path in the local domain.

Abstract: The verification of fault-tolerant connections between redundant controller pairs and nodes is provided. In particular, a node identifier seen at one port of the controllers is compared to the node identifier seen at another port of the controllers. In response to determining that proper connections have not been made, an error or warning signal may be generated. In addition, where supported by dynamic port configuration, the ports of the controllers may be reconfigured in response to the comparison to effect proper connections. In response to determining that proper connections have been made, a signal verifying that proper connections have been made may be generated.

Abstract: A network storage appliance is disclosed. The appliance includes a chassis enclosing a backplane, and a server enclosed in the chassis and coupled to the backplane. The appliance also includes storage controllers enclosed in the chassis, each coupled to the backplane, which control transfer of data between the server and storage devices coupled to the storage controllers. The storage controllers also control transfer of data between the storage devices and computers networked to the appliance and external to the appliance. The storage controllers and the server comprise a plurality of hot-replaceable blades. Any one of the plurality of blades may be replaced during operation of the appliance without loss of access to the storage devices by the computers. In one embodiment, the server executes storage application software, such as backup software for backing up data on the storage devices, such as to a tape device networked to the server.

Abstract: A network storage appliance is disclosed. The storage appliance includes a port combiner that provides data communication between at least first, second, and third I/O ports; a storage controller that controls storage devices and includes the first I/O port; a server having the second I/O port; and an I/O connector for networking the third I/O port to the port combiner. A single chassis encloses the port combiner, storage controller, and server, and the I/O connector is affixed on the storage appliance. The third I/O port is external to the chassis and is not enclosed therein. In various embodiments, the port combiner comprises a FiberChannel hub comprising a series of loop resiliency circuits, or a FiberChannel, Ethernet, or Infiniband switch. In one embodiment, the port combiner, I/O ports, and server are all comprised in a single blade module for plugging into a backplane of the chassis.

Abstract: A SAS expander adaptively configures a Serial-Attached-SCSI (SAS) PHY to accommodate varying lengths of a cable coupling the PHY to a remote PHY. The expander (a) configures the SAS PHY with settings of an entry of a table of PHY configuration settings, each entry in the table having different PHY configuration setting values; (b) clears a counter; (c) operates the PHY to communicate with the remote PHY for a monitoring period, after configuring the PHY and clearing the counter; (d) increments the counter when the PHY detects a PHY event during the monitoring period, and otherwise decrements the counter; (e) repeats steps (c) and (d) unless the counter rises above a threshold; and (f) when the counter rises above the threshold, repeats steps (a) through (e), wherein step (a) is performed with the settings of a different entry of the table.

Abstract: A network storage appliance is disclosed. The storage appliance includes a port combiner that provides data communication between at least first, second, and third I/O ports; a storage controller that controls storage devices and includes the first I/O port; a server having the second I/O port; and an I/O connector for networking the third I/O port to the port combiner. A single chassis encloses the port combiner, storage controller, and server, and the I/O connector is affixed on the storage appliance. The third I/O port is external to the chassis and is not enclosed therein. In various embodiments, the port combiner comprises a FibreChannel hub comprising a series of loop resiliency circuits, or a FibreChannel, Ethernet, or Infiniband switch. In one embodiment, the port combiner, I/O ports, and server are all comprised in a single blade module for plugging into a backplane of the chassis.

Abstract: A network storage appliance is disclosed. The appliance includes a chassis enclosing a backplane, and a server enclosed in the chassis and coupled to the backplane. The appliance also includes storage controllers enclosed in the chassis, each coupled to the backplane, which control transfer of data between the server and storage devices coupled to the storage controllers. The storage controllers also control transfer of data between the storage devices and computers networked to the appliance and external to the appliance. The storage controllers and the server comprise a plurality of hot-replaceable blades. Any one of the plurality of blades may be replaced during operation of the appliance without loss of access to the storage devices by the computers. In one embodiment, the server executes storage application software, such as backup software for backing up data on the storage devices, such as to a tape device networked to the server.

Abstract: A system and method for optimizing accesses to storage devices based on RAID I/O request characteristics is disclosed. A current I/O request processed by a storage controller is analyzed for relative locality to a previous I/O request, and adjusted over time such that storage device accesses will be efficiently conducted with respect to sequential or random workloads. A storage device access profile is maintained for each storage device based on sequential or random locality characteristics of previous RAID I/O requests. The chunk locations of the two most recent accesses are sampled according to predetermined criteria in order to create a storage device access profile, which governs queue depth and I/O size parameters used to communicate with storage devices. By managing I/O requests to storage devices using this invention, performance of such a storage controller will be optimized for changing random and sequential workloads.

Abstract: A network storage appliance including one or more integrated switching devices is disclosed. The appliance includes redundant storage controllers that transfer frames of data between storage devices and host computers. The integrated switching devices include a plurality of I/O ports and a data transfer path between each of the I/O ports for providing simultaneous data transfers between multiple pairs thereof. The switches enable the appliance to simultaneously transfer frames between its I/O ports and storage device I/O ports and/or host I/O ports, thereby providing increased data transfer bandwidth over arbitrated loop configurations. Additionally, the switches are intelligent and may be programmed to achieve improved fault isolation. The appliance may also include servers that include I/O ports coupled to the switches for simultaneously transferring data with the storage controllers and/or I/O ports of devices external to the appliance.

Abstract: A method, device, and system are provided for the automatically assigning identification numbers or enclosure IDs to enclosures in a data storage system. Each enclosure is assigned a unique enclosure ID that can be used to reference the enclosure in the data storage system. The enclosure IDs are generated and assigned to enclosures based on the network topology. Specifically, each enclosure is assigned an enclosure ID that not only uniquely identifies the enclosure but the enclosure ID can be used to determine the location of the enclosure in the data storage system.

Abstract: A SAS expander includes SAS PHYs for transceiving signals with SAS devices on corresponding SAS links coupled to the SAS PHYs. The SAS expander includes status registers that provide fault detection parameters concerning communications on the SAS links. A microprocessor of the SAS expander identifies faulty communications on one of the SAS links, based on the fault detection parameters, and disables a corresponding one of the SAS PHYs coupled to the SAS link on which the microprocessor identified the faulty communications. The microprocessor may also report the PHY disabling to a SAS initiator. The microprocessor may also re-enable the PHY after corrective action is taken, such as in response to user input, an indication from a SAS device, or automatically detecting the corrective action. The expander may also automatically take the corrective action. The fault detection parameters may include error counters and corresponding thresholds, interrupt indicators, and state values.

Abstract: A storage system includes two RAID controllers, each having two SAS initiators coupled to a zoning SAS expander. The expanders are linked by an inter-controller link and create a SAS ZPSDS. The expanders have PHY-to-zone mappings and zone permissions to create two distinct SAS domains such that one initiator of each RAID controller is in one domain and the other initiator is in the other domain. The disk drives are dual-ported, and each port of each drive is in a different domain. Each initiator can access every drive in the system, half directly through the local expander and half indirectly through the other RAID controller's expander via the inter-controller link. Thus, a RAID controller can continue to access a drive via the remote path in the remote domain if the drive becomes inaccessible via the local path in the local domain.