A data storage system includes multiple head nodes and data storage sleds. Volume data is replicated between a primary and one or more secondary head nodes for a volume partition and is further flushed to a set of mass storage devices of the data storage sleds. Volume metadata is maintained in a primary and one or more secondary head nodes for a volume partition and is updated in response to volume data being flushed to the data storage sleds. Also, the primary and secondary head nodes store check-points of volume metadata to the data storage sleds, wherein in response to a failure of a primary or secondary head node for a volume partition, a replacement secondary head node for the volume partition recreates a secondary replica for the volume partition based, at least in part, on a stored volume metadata checkpoint.

In one aspect there is provided a method. The method may include generating a graphical representation of a decision logic underlying a solution, the graphical representation having a plurality of nodes. A component archetype can be identified. The identified component archetype can support generating a function implementing one of the plurality of nodes in the graphical representation of the solution. An instance of the component can be generated based at least on the component archetype. The function can be generated by invoking the instance of the component. The generated function can be hosted by the instance of the component. Alternately and/or additionally, the generation function can be copied into one or more separate execution environments. Systems and articles of manufacture, including computer program products, are also provided.

A method and system are provided for spare capacity usage for critical redundancy in storage arrays. The method may include monitoring a Redundant Array of Independent Disks (RAID) array to determine whether one or more redundancy units are at a critical level. A redundancy unit may be in a critical level when an additional drive failure will result in loss of data from the redundancy unit. The method may further include identifying available regions in the RAID array which are not allocated to user data in response to determining that a particular redundancy unit is critical. The method may further include determining an available region for the particular redundancy unit, where the available region is in a drive of the RAID array that does not contain data of the particular redundancy unit. The method may further include storing a critical stripe in the available region.

A hybrid storage device that includes a hard-disk drive (HDD) and a flash memory is described. When control logic in the hybrid storage device receives a request from an external device to write a block of data to a logical address in a first portion of an address space that maps to the HDD, the control logic writes the block of data to the HDD. However, if there is a change in environmental state information of the hybrid storage device during the write operation, the control logic writes at least a portion of the block of data to a logical address for the block of data in a second portion of the address space which maps to the flash memory. Note that the address space may be common to the external device and the hybrid storage device.

An embodiment of a circuit includes a data latch and a plurality of cascaded latches, wherein a first of the plurality of cascaded latches is configured to receive a first signal from the data latch and each subsequent cascaded latch is configured to receive a data output signal of a preceding cascaded latch, and an error-detection circuit configured to receive the respective data output signals and detect error in operation of the cascaded latches based thereon.

A failover system, server, method, and computer readable medium are provided. The system includes a primary server for communicating with a client machine and a backup server. The primary server includes a primary session manager, a primary dispatcher a primary order processing engine and a primary verification engine. The method involves receiving an input message, obtaining deterministic information, processing the input message and replicating the input message along with the deterministic information.

Sync-mark (SM) detection recovery techniques for HDDs tend to be slow and cumbersome. Typical approaches often require an entire read command to be aborted and multiple subsequent read commands with significant firmware intervention. Should a data sector be unreadable, an example recovery technique for HDDs is recursive read averaging (RRA). Using RRA, samples for failed sector reads are stored in memory. When a sector is subsequently read, the samples are averaged and replace the prior sample stored in memory. The averaged samples are then used to decode the sector. Should SMs associated with data fragments making up a sector be unreadable, the data fragments are unreadable, rendering the sector unreadable. The systems and methods described herein are used to recover previously unreadable SMs. When updated data fragments are subsequently recombined, the confidence level in the overall sector is improved, which increases the likelihood of a successful decode of the sector.

A computer cluster includes a group of connected computers that work together essentially as a single system. Each computer in the cluster is called a node. Each node has a boot device configured to load an image of an operating system into the node's main memory. Sometimes the boot device of a first node experiences a problem that prevents the operating system from loading. This can affect the entire cluster. Some aspects of the disclosure, however, are directed to operations that determine the problem with the first node's boot device based on a communication sent via a first communications network. Further, the operations can communicate to the first node a copy of boot data from a second node's boot device. The copy of the boot data is sent via a second communications network different from the first communications network. The copy of the boot data can solve the first boot device's problem.

Memory system enabling memory mirroring in single write operations. The memory system includes a memory channel which can store duplicate copies of a data element into multiple locations in the memory channel. The multiple locations are disposed in different memory modules and have different propagation times with respect to a data signal transmitted from the memory controller. In a write operation, the relative timings of the chip select, command and address signals among the multiple locations are adjusted according to the data propagation delay. As a result, a data element can be written into the multiple locations responsive to a data signal transmitted from the memory controller in a single transmission event.

A failure detection circuit for a motor vehicle electronic computer, including: a main microcontroller having at least two microcontroller cores configured to execute the same instructions in parallel, and at least one first software module providing a critical function of a motor vehicle. The first software module includes a predetermined input point and a predetermined output point a supervision microcontroller and a synchronous communication interface for coupling the main microcontroller and the supervision microcontroller so as to enable mutual supervision. The detection circuit makes it possible to detect systematic and random failures.