Fullness control for media-based cache operating in a steady state

摘要

A data storage system incorporating a write-caching subsystem that implements a steady-state media-based cache is described. The steady-state of the media-based cache can be obtained by directing non-sequential write commands and data received from the host device to multiple independent cache locations and, thereafter, selectively copying or moving such data between the caches so that none of the caches are either too full or too empty. In this manner, a non-sequential write command can be cached in a power-safe manner until it is efficient and/or convenient to write such data to the mainstore portion of the physical media.

主权项

1. A method of caching write commands received by a data storage system from a host, the data storage system comprising a physical media and a write-caching subsystem, the method comprising:
receiving a write command from a host; determining an aggregate fullness status of the write-caching subsystem, the write-caching subsystem comprising a volatile memory and a media-based cache, the aggregate fullness based on a fullness status of at least a portion of the media-based cache; selecting, based on a state of the write-caching subsystem, an action to be performed, the action selected from:
reducing the aggregate fullness status of the write-caching subsystem; andservicing a command from the host that is not managed by the write-caching subsystem; and performing the selected action.