Hewlett Packard Enterprise Development LP

Nimble Storage, Inc.

Senthil Kumar Ramamoorthy

Umesh Maheshwari

Pradeep Shetty

Vanco Buca

Hy Dinh Vu

Sandeep Karmarkar

Mukul Kumar Singh

Gurunatha Karaje

Rajat Sharma

Srikant Varadan

Methods, systems, and programs are presented for managing a storage device memory. One method includes an operation for receiving a request to pin a volume stored in the storage device. The device includes disk storage and a solid state drive (SSD) cache, where pinned volumes in the storage device have all active volume data in the SSD cache. Further, the method includes an operation for determining the maximum amount of pinnable space in the SSD cache, the maximum amount of pinnable space being calculated based on the sizes of the disk storage and the SSD cache. Further, the method includes operations for determining the available pinning space, which is the maximum amount of pinnable space minus the current amount of pinned data in the SSD cache, and for granting the request to pin the volume when the available pinning space is greater than or equal to a size of the volume.

Updating of pinned storage in flash based on changes to flash-to-disk capacity ratio

When data blocks of a data seglet are compressed using a shared dictionary and when the requested data block (or blocks) do not include the last data block of the data seglet, an optimization in the read path may involve decompressing a certain portion of the data seglet from a starting position of the data seglet to a decompression endpoint of the data seglet, but not including the portion of the data seglet following the decompression endpoint. Such technique may involve the storing of a mapping that maps, for each data block within the data seglet, an identifier of the data block to a decompression endpoint that indicates a portion of the data seglet that includes the data block.

Methods and systems for efficiently reading a data block from a data seglet with compressed data blocks

Methods and systems are presented for allocating CPU cycles among processes in a storage system. One method includes operations for maintaining segments in a first memory, each segment including blocks, and for maintaining a block temperature for each block in a second memory. The first memory is a read-cache where one segment is written at a time, and each block is readable from the first memory without reading the corresponding complete segment. The block temperature is based on the frequency of access to the respective block, and a segment temperature is based on the block temperature of its blocks. Additionally, the segment with the lowest segment temperature is selected for eviction from the second memory, and blocks in the selected segment with a block temperature greater than a threshold temperature are identified. The selected segment is evicted, and a segment with the identified blocks is written to the first memory.

Access-based eviction of blocks from solid state drive cache memory

Methods and systems are presented for evicting or copying-forward blocks in a storage system during garbage collection. In one method, a block status is maintained in a first memory to identify if the block is active or inactive, blocks being stored in segments that are configured to be cacheable in a second memory, a read-cache memory. Whenever an operation on a block is detected making the block inactive in one volume, the system determines if the block is still active in any volume, the block being cached in a first segment in the second memory. When the system detects that the first segment is being evicted from the second memory, the system re-caches the block into a second segment in the second memory if the block status of the block is active and the frequency of access to the block is above a predetermined value.

Cache eviction of inactive blocks using heat signature

Management of pinned storage in flash based on flash-to-disk capacity ratio

Described herein are methods, systems and machine-readable media for simulating a FIFO cache using a Bloom filter ring, which includes a plurality of Bloom filters arranged in a circular log. New elements are registered in the Bloom filter at the head of the circular log. When the Bloom filter at the head of the circular log is filled to its capacity, membership information associated with old elements in the Bloom filter at the tail of the circular log is evicted (simulating FIFO cache behavior), and the head and tail of the log are advanced. The Bloom filter ring is used to determine cache statistics (e.g., cache hit, cache miss) of a FIFO cache of various sizes. In response to simulation output specifying cache statistics for FIFO cache of various sizes, a FIFO cache is optimally sized.

Growing community of inventors

Sunnyvale, CA, United States of America

Senthil Kumar Ramamoorthy