A method for a cache miss estimation includes; generating a variable range of a possible value of loop variables relevant to a specific array; generating first expression of number of times indicating the number of times the specific position of a specific loop is executed; generating second expression of number of times indicating the number of times the data of the access target is stored in the cache; generating third expression of number of times indicating the number of times the data of the access target is removed from the cache; generating fourth expression of number of times, from a generated conflict miss cause common expression, indicating the number of times the data of the access target is stored in the cache; and estimating a number of cache miss based on the difference between the first and the second expressions and the difference between the third and the forth expressions.

There is provided a storage having plural clusters. Each of the clusters includes a cache memory and a save memory. The processor of each of the clusters controls to write plural data pieces into the cache memory, controls to store all the data stored in the cache memory into the save memory upon an occurrence of a failure, and controls to restore some of the data stored in the save memory into the cache memory upon recovery from the failure.

A data storage device is disclosed comprising a volatile memory, a primary and a first secondary non-volatile memory (NVM), and control circuitry coupled to the volatile memory and the primary and first secondary NVM and configured to (a) write metadata and user data associated with a host write command to the volatile memory; (b) write the user data to the primary NVM; (c) continue to write metadata associated with each of one or more host write commands to the volatile memory, and when a first condition is met, write metadata that has accumulated in the volatile memory to the first secondary NVM; and (d) repeat (c), and when a second condition is met, then write at least a portion of the metadata that has accumulated in the first secondary NVM or the volatile memory to the primary NVM.

A system includes a read/write module and a caching module. The read/write module is configured to access a first portion of a recording surface of a rotating storage device. Data is stored on the first portion of the recording surface of the rotating storage device at a first density. The caching module is configured to cache data on a second portion of the recording surface of the rotating storage device at a second density. The second portion of the recording surface of the rotating storage device is separate from the first portion of the recording surface of the rotating storage device. The second density is less than the first density.

An electronic device includes a first storage unit, a second storage unit and a control unit. The first storage unit stores the cache of the data. The second storage unit stores the data. The control unit calculates a first ratio of the cache corresponding to the data according to the capacity of the first storage unit. The control unit sends a distribution signal to the processing unit when the control unit reads the data from the second storage unit. The processing unit obtains a first distribution result corresponding to the cache according to the first ratio, and stores the cache to the first storage unit according to the first distribution result.

Methods and apparatuses are provided for reducing the number of write operations to a flash-based storage system that stores and replaces data. The storage system includes a first storage implemented using non-flash storage and a second storage implemented using flash memory. Missed data is first stored in the first storage, which can be less sensitive than flash to write operations. The missed data is stored in the flash-based second storage only after the missed data satisfies a storage management algorithm.

Inventive aspects include a heterogeneous unified memory section, which includes an extended unified memory space across a plurality of physical heterogeneous memory modules. A cold page reclamation logic section can receive and prioritize cold pages from a system memory. The cold pages can include a first subset of memory pages having a first type of memory data and a second subset of memory pages having a second type of memory data. For example, the cold pages can include anon-type memory pages and file-type memory pages. A dynamic tuning logic section can manage space allocation within the extended unified memory space. An intelligent page sort logic section can distribute the cold pages among different pools of physical heterogeneous memory modules based on varying characteristics of the pools, and based on the assigned priorities.

A storage system includes a first storage controller including a plurality of main storage media and one or more processor cores, and a second storage controller including a plurality of main storage media and one or more processor cores and performing communication with the first storage controller. Storage areas of the main storage media in the first storage controller are allocated to an address map. In response to the occurrence of failures in one or mode main storage media of the main storage media of the first storage controller, the first storage controller performs restarting to reallocate the storage areas of the main storage media excluding one or more main storage media having caused the failures to an address map reduced than before the occurrence of the failures. The second storage controller continues operating during the restarting of the first storage controller.

Systems and methods are provided for expanding the available memory of a storage controller. The systems and methods utilize a PCIe memory controller connected to the backend interface of the storage controller. Memory of the PCIe memory controller is memory mapped to controller memory of the storage controller. The PCIe connection allows the storage controller to access the memory of the PCIe memory controller with latencies similar to that of the controller memory.

A computer includes a memory and a cache holding a part of data stored in the memory in any of a plurality of data regions. In a case of replacing first data of a first data size held in the cache with second data of a second data size larger than the first data size, allocation of data regions of the cache is changed in units of the second data size by referring to a first management list that includes a plurality of first entries that correspond to the plurality of data regions, respectively, for managing priorities of the data regions for each of the plurality of processes, and a second management list that includes a plurality of second entries corresponding to the first entries for a process that uses the first data size, for managing priorities of first data of the first data size held in the data regions.