Techniques described herein relate to systems and methods of data storage, and more particularly to providing layering of file system functionality on an object interface. In certain embodiments, file system functionality may be layered on cloud object interfaces to provide cloud-based storage while allowing for functionality expected from a legacy applications. For instance, POSIX interfaces and semantics may be layered on cloud-based storage, while providing access to data in a manner consistent with file-based access with data organization in name hierarchies. Various embodiments also may provide for memory mapping of data so that memory map changes are reflected in persistent storage while ensuring consistency between memory map changes and writes. For example, by transforming a ZFS file system disk-based storage into ZFS cloud-based storage, the ZFS file system gains the elastic nature of cloud storage.

Systems, apparatuses, and methods related to three tiered hierarchical memory systems are described herein. A three tiered hierarchical memory system can leverage persistent memory to store data that is generally stored in a non-persistent memory, thereby increasing an amount of storage space allocated to a computing system at a lower cost than approaches that rely solely on non-persistent memory. An example apparatus may include a persistent memory, and one or more non-persistent memories configured to map an address associated with an input/output (I/O) device to an address in logic circuitry prior to the apparatus receiving a request from the I/O device to access data stored in the persistent memory, and map the address associated with the I/O device to an address in a non-persistent memory subsequent to the apparatus receiving the request and accessing the data.

Methods, apparatus, systems and articles of manufacture are disclosed to utilize non-volatile memory for computer system boot. An example processor platform includes a non-volatile memory coupled to a processing unit via a bus, and a microcontroller to: configure the processing unit to store, on the non-volatile memory, a heap and a stack for execution of boot code, and configure the processing unit to execute the boot code stored on the non-volatile memory.

A method for maintaining statistics for data elements in a cache is disclosed. The method maintains a heterogeneous cache comprising a higher performance portion and a lower performance portion. The method maintains, within the lower performance portion, a ghost cache containing statistics for data elements that are currently contained in the heterogeneous cache, and data elements that have been demoted from the heterogeneous cache within a specified time interval. The method calculates a size of the ghost cache based on an amount of frequently accessed data that is stored in backend storage volumes behind the heterogeneous cache. The method alters the size of the ghost cache as the amount of frequently accessed data changes. A corresponding system and computer program product are also disclosed.

A system and method improve caching efficiency in a data storage system by performing machine learning processes on metadata relating to extents of data blocks, rather than individual blocks themselves. Thus, once the storage devices are divided into extents, various metadata regarding access to the blocks within each extent are aggregated, and per-extent features are extracted. These features are used to train a data regression model that is subsequently used to infer a most likely “hotness” value for each extent at a future time. These predicted values, which may be further classified as e.g. “hot”, “warm”, and “cold” using thresholds, are used to implement the cache replacement policy. Embodiments scale to large and multi-layered caches, and may avoid common caching problems like thrashing, by adjusting the extent size. Policy goal functions may be optimized by dynamically adjusting the classification thresholds.

A method for constructing a persistent memory index in a non-uniform memory access architecture includes: maintaining partial persistent views in a persistent memory and maintaining a global volatile view in a DRAM; an underlying persistent memory index processing a request in a foreground thread when cold data is accessed; when hot data is accessed, reading a key-value pair for a piece of hot data in the global volatile view in response to a query operation carried in the request, and in response to an insert/update/delete operation carried in the request, updating a local partial persistent view and the global volatile view; and in response to a hotspot migration, a background thread generating new partial persistent views and a new global volatile view, and recycling the partial persistent views and the global volatile view for old hot data into the underlying persistent memory index.

A data storage system provides persistent storage in bulk non-volatile memory. A controller of the data storage system receives a host write command and buffers associated host write data in both a first write cache in non-volatile memory and a mirrored second write cache in volatile memory. The controller destages the host write data to the bulk non-volatile memory from the second write cache but not the first write cache. The controller services relocation write commands requesting data relocation within the bulk non-volatile memory by reference to the second write cache. Servicing the relocation write commands includes buffering relocation write data in the second write cache but not the first write cache and destaging the relocation write data to the bulk non-volatile memory from the second write cache.

Various embodiments of a distributed numeric sequence generation system and method are described. In particular, some embodiments provide high-scale, high-availability, low-cost and low-maintenance numeric sequence generation in a non-Relational Database Management System (“non-RBMS”) system by sacrificing monotonicity. The distributed numeric sequence generation system comprises a plurality of hosts, wherein individual hosts implement a cache for caching a plurality of numeric sequences. A host can access master numeric sequence data at a separate system to obtain values for numeric sequences to store in its cache. A host can receive a request from a client for values of a numeric sequence, and provide to the client the values for the numeric sequence from its cache. Some embodiments of the distributed numeric sequence generation system and method are also equipped to vend recyclable and bounded numeric sequences.

A storage device is provided to comprise a memory device for storing data, a cache memory device including a first cache memory configured to cache certain data stored in the memory device and a second cache memory configured to store data evicted from the first cache memory, and a memory controller configured to receive a read request for first data from a host, evict second data from the first cache memory based on a reuse distance of the second data, store the second data in the second cache memory, load the first data to the first cache memory, and transmit the first data to the host.

A microcontroller includes a memory, direct memory access (DMA) controllers and a microprocessor. The microprocessor maintains one or more memory protection (MP) configurations to control access to protected memory areas of the microcontroller. In response to a secure service call of an unsecure user-application, the microprocessor executes a state machine which disables interrupt requests, determining whether DMA controller configurations and MP configurations satisfy secure-service criteria. When the secure-service criteria are satisfied, at least one secure operation associated with the secure service call is performed, and memory areas accessed during the execution of the at least one secure operation are cleaned. The interrupt requests are re-enabled and a response to the secure service call is generated.