Prioritization for cache systems

摘要

In a data storage environment, a caching system includes a synchronous I/O module to stage cache promotions, and an asynchronous I/O module to de-stage cache promotions. To reduce the likelihood that high priority cache promotions are not skipped, the caching system associations a configurable priority level with each logical storage device, and prioritizes cache promotions accordingly. Related methods are also described.

主权项

1. A method comprising:
receiving a first request to read first data; determining the first data is not available in a cache device; requesting the first data from a first storage device; determining to promote the first data to cache based at least in part upon a first priority level associated with the first storage device; copying the first data received from the first storage device to a cache promotion staging data structure, the cache promotion staging data structure comprising information about pending cache promotions; receiving a second request to read second data; determining the second data is not available in the cache device; requesting the second data from a second storage device; determining to promote the second data to cache based at least in part upon a second priority level associated with the second storage device; determining there are insufficient resources to copy the second data to the cache promotion staging data structure; determining to replace the first data in the cache promotion staging data structure with the second data based at least in part upon comparing the first priority level associated with the first storage device to the second priority level associated with the second storage device; replacing, in the cache promotion staging data structure, the first data with the second data received from the second storage device, wherein replacing the first data in the cache promotion staging data structure causes the first data not to be moved to the cache device; and moving the second data from the cache promotion staging data structure to the cache device.