Flash memory cache including for use with persistent key-value store

摘要

Described is using flash memory, RAM-based data structures and mechanisms to provide a flash store for caching data items (e.g., key-value pairs) in flash pages. A RAM-based index maps data items to flash pages, and a RAM-based write buffer maintains data items to be written to the flash store, e.g., when a full page can be written. A recycle mechanism makes used pages in the flash store available by destaging a data item to a hard disk or reinserting it into the write buffer, based on its access pattern. The flash store may be used in a data deduplication system, in which the data items comprise chunk-identifier, metadata pairs, in which each chunk-identifier corresponds to a hash of a chunk of data that indicates. The RAM and flash are accessed with the chunk-identifier (e.g., as a key) to determine whether a chunk is a new chunk or a duplicate.

主权项

1. In a computing environment, a system comprising:
a RAM-based index; and a storage mechanism configured to maintain data items in pages, with at least some of the pages in a secondary storage device, the storage mechanism configured to access the RAM-based index to determine whether a data item is retrievable, returning information corresponding to one or more pages in which the data item is maintained, the storage mechanism further comprising a RAM-based write buffer configured to maintain data items to be written to the secondary storage device, and the storage mechanism further configured to write a page of data items from the RAM-based write buffer to the secondary storage device on determining that the data items fill a page, or write less than a page of data items from the RAM-based write buffer to the secondary store device when a coalesce time is reached.