A method for demoting a selected storage element from a cache memory includes storing favored and non-favored storage elements within a higher performance portion and lower performance portion of the cache memory. The method maintains a plurality of favored LRU lists and a non-favored LRU list for the higher and lower performance portions of the cache memory. Each favored LRU list contains entries associated with the favored storage elements that have the same unique residency multiplier. The non-favored LRU list includes entries associated with the non-favored storage elements. The method demotes a selected favored or non-favored storage element from the higher and lower performance portions of the cache memory according to a cache demotion policy that provides a preference to favored storage elements over non-favored storage elements based on a computed cache life expectancy, residency time, and the unique residency multiplier. A corresponding storage controller and computer program product are also disclosed.

A method for demoting a selected storage element from a cache memory includes storing favored and non-favored storage elements within a higher performance portion and lower performance portion of the cache memory. The favored storage elements are retained in the cache memory longer than the non-favored storage elements. The method maintains a first favored LRU list and a first non-favored LRU list, associated with the favored and non-favored storage elements stored within the higher performance portion of the cache. The method selects a favored or non-favored storage element to be demoted from the higher performance portion of the cache memory according to life expectancy and residency of the oldest favored and non-favored storage elements in the first LRU lists. The method demotes the selected from the higher performance portion of the cache to the lower performance portion of the cache, or to the data storage devices, according to a cache demotion policy. A corresponding storage controller and computer program product are also disclosed.

Techniques for processing I/O operations may include: receiving, at a data storage system, a write operation that writes first data to a target logical address of a log, wherein the data storage system includes a first storage tier of rotating non-volatile storage devices and a second tier of non-volatile solid state storage devices; storing the first data of the target logical address in a first level cache; destaging the first data from the first level cache to a first physical storage location in the first storage tier; and determining, in accordance with first read activity information for the target logical address, whether to store the first data for the target logical address in a second level cache including at least a portion of the non-volatile solid state storage devices of the second tier. The second level cache is a content addressable caching layer that caches data based on read activity.

In a storage system that implements metadata paging, the page free pool is replenished in the background to reduce foreground evictions and associated latency on page-in. A two-level page eviction controller with cascaded proportional, integral, derivative (PID) controllers optimizes the size of the free page pool and optimizes the rate at which pages are freed in the background. By optimizing these two parameters the page eviction controller dynamically maximizes used pages (minimizing free pages) to increase the metadata cache hit ratio. Optimizing the parameters also reduces the chances of foreground page evictions, thereby reducing IO latency, during both steady state and burst page-in requests.

A system and method comprising: receiving a request to write data stored at a first range of a first volume to a second range of a second volume, where first metadata for the first range of the first volume is associated with a range of physical addresses where the data is stored in the storage system; and responsive to receiving the request: creating second metadata for the second range of the second volume, wherein the second metadata is associated with the range of physical addresses where the data is stored in the storage system; and associating the second volume with the second metadata.

The present disclosure includes apparatuses and methods related to a memory protocol. An example apparatus can perform operations on a number of block buffers of the memory device based on commands received from a host using a block configuration register, wherein the operations can read data from the number of block buffers and write data to the number of block buffers on the memory device.

A memory system includes an interface circuit configured to connect to a host device, a controller electrically connected to the interface circuit, and a nonvolatile semiconductor memory electrically connected to the controller. The controller is configured to transmit a first response in response to a power supplied from the host device via the interface circuit, upon receipt of a first command from the host device after transmitting the first response, determine a status of data stored in the nonvolatile semiconductor memory, and transmit to the host device a second response including the determined status of the data stored in the nonvolatile semiconductor memory.

Delaying deletion of a dataset, including: associating an eradication timer with the dataset, wherein the eradication timer specifies an amount of time to delay a requested deletion of the dataset; determining that the amount of time to delay the requested deletion of the dataset should be modified; and modifying the eradication timer to specify a modified amount of time to delay the requested deletion of the dataset.

A method comprising: receiving, at a block device interface, an instruction to write data, the instruction comprising a memory location of the data; copying the data to pinned memory; performing, by a vector processor, one or more invertible transforms on the data; and writing the data from the pinned memory to one or more storage devices asynchronously; wherein the pinned memory of the data corresponds to a location in pinned memory, the pinned memory being accessible by the vector processor and one or more other processors.

A storage server and a method of driving the storage server are provided. The storage server includes a processor configured to: generate a plurality of flush write commands based on a write command of first data provided from a host, provide a replication command corresponding to the write command to an external storage server, and receive an operation completion signal of the replication command from the external storage server; a memory storing a program of a log file to which the plurality of flush write commands are logged; and a storage device configured to receive a multi-offset write command including one or more flush write commands logged to the log file, and perform a flush operation on the multi-offset write command. The processor is further configured to provide the multi-offset write command to the storage device based on the log file after receiving the operation completion signal.