A storage subsystem includes a variable-size write buffer that temporarily stores write data received from a host system. The storage subsystem is capable of adjusting the size of the write buffer so as to vary both the performance (e.g., sustained write speed) of the storage subsystem and a risk of data loss. In one embodiment, the storage subsystem implements a command set that enables the host system to directly control the size of the write buffer. The storage subsystem may additionally or alternatively be capable of adjusting the size of the write buffer based on monitored operating conditions, such as the temperature, the stability/consistency of a power signal received from the host system, and/or the elapsed time since the storage subsystem was last powered up.

Storage subsystem with configurable buffer

Embodiments of the invention are directed to systems and methods for reducing an amount of backup power needed to provide power fail safe preservation of a data redundancy scheme such as RAID that is implemented in solid state storage devices where new write data is accumulated and written along with parity data. Because new write data cannot be guaranteed to arrive in integer multiples of stripe size, a full stripe's worth of new write data may not exist when power is lost. Various embodiments use truncated RAID stripes (fewer storage elements per stripe) to save cached write data when a power failure occurs. This approach allows the system to maintain RAID parity data protection in a power fail cache flush case even though a full stripe of write data may not exist, thereby reducing the amount of backup power needed to maintain parity protection in the event of power loss.

System and method for maintaining a data redundancy scheme in a solid state memory in the event of a power loss

Systems and methods are provided for managing asynchronous replication in a distributed database environment, while providing for scaling of the distributed database. A cluster of nodes can be assigned roles for managing partitions of data within the database and processing database requests. In one embodiment, each cluster includes a node with a primary role to process write operations and mange asynchronous replication of the operations to at least one secondary node. Each cluster or set of nodes can host one or more partitions of database data. Collectively, the cluster or set of nodes define a shard cluster that hosts all the data of the distributed database. Each shard cluster, individual nodes, or sets of nodes can be configured to manage the size of any hosted partitions, splitting database partitions, migrating partitions, and/or managing expansion of shard clusters to encompass new systems.

Large distributed database clustering systems and methods

Embodiments of the invention are directed to systems and methods for improving wear leveling performance in solid-state memory. The embodiments described herein make more consistent the number of wear leveling operations that needs to be performed, so that sudden spikes in the number wear leveling operations may be reduced in solid-state memory. In one embodiment, a staggered threshold-based wear leveling approach is used to spread out the execution of wear leveling operations that otherwise would have been triggered in clusters. Under the staggered threshold-based approach, wear leveling is periodically triggered by different wear leveling thresholds that are associated with various units of solid-state memory such as a group of blocks, so that only a certain amount of units are wear leveled at any given time.

System and method for improving wear-leveling performance in solid-state memory

A storage subsystem is disclosed that maintains (a) statistics regarding errors detected via an ECC (error correction code) module of the storage subsystem; and/or (b) historical data regarding operating conditions experienced by the storage subsystem, such as temperature, altitude, humidity, shock, and/or input voltage level. The storage subsystem, and/or a host system to which the storage subsystem attaches, may analyze the stored data to assess a risk of a failure event such as an uncorrectable data error. The results of this analysis may be displayed via a user interface of the host system, and/or may be used to automatically take a precautionary action such as transmitting an alert message or changing a mode of operation of the storage subsystem.

Solid state storage subsystem that maintains and provides access to data reflective of a failure risk

A non-volatile solid-state storage subsystem, such as a non-volatile memory device, maintains usage statistics reflective of the wear state, and thus the remaining useful life, of the subsystem's memory array. A host system reads the usage statistics information, or data derived therefrom, from the subsystem to evaluate the subsystem's remaining life expectancy. The host system may use this information for various purposes, such as to (a) display or report information regarding the remaining life of the subsystem; (b) adjust the frequency with which data is written to the subsystem; and/or (c) select the type(s) of data written to the subsystem.

Systems and methods for measuring the useful life of solid-state storage devices

A storage subsystem comprises a set of zone definitions that uses physical block addresses to divide a memory array in the storage subsystem into zones or segments. A set of zone parameters defines user access modes and security levels for each of the segments. Defining zones for the memory array provide flexibility and increased protection for data stored in the memory array. For example, data of one zone can be quickly erased without affecting data stored in other zones and critical data can be stored in read-only zones to prevent inadvertent overwrite.

Systems and methods for storing data in segments of a storage subsystem

A solid-state storage subsystem, such as a non-volatile memory card or drive, includes a main memory area that is accessible via standard memory access commands (such as ATA commands), and a restricted memory area that is accessible only via one or more non-standard commands. The restricted memory area stores information used to control access to, and/or use of, information stored in the main memory area. As one example, the restricted area may store one or more identifiers, such as a unique subsystem identifier, needed to decrypt an executable or data file stored in the main memory area. A host software component is configured to retrieve the information from the subsystem's restricted memory area, and to use the information to control access to and/or use of the information in the main memory area.

Gary A. Drossel

Papers

Systems and methods for measuring the useful life of solid-state storage devices

Systems and methods for storing data in segments of a storage subsystem

System for controlling use of a solid-state storage subsystem

Systems and methods for segmenting and protecting a storage subsystem

Solid-state storage subsystem security solution