System and method for adjusting performance of a media storage by decreasing a maximum throughput by a primary derate parameter to specify available & guaranteed rate parameters and determining ring buffer sizes for streams

Abstract

A system and method for tuning a storage system may include characterizing a maximum sustainable throughput for the storage system. The maximum sustainable throughput may be decreased by a primary derate parameter to obtain a primary throughput. Sizes for buffer units may be determined at different stream rates, where during operation the buffer units buffer a data stream between a stream requester and storage. Buffer unit sizes may be determined by generating stream simulators sufficient to consume the primary throughput and then optimizing the buffer sizes to prevent underruns. This may be repeated at different stream rates to determine a table of buffer sizes. The primary throughput may be decreased by a secondary derate parameter to obtain a maximum system bandwidth which sets an upper limit on admission of streams. When buffer sizes are determined, a prefill margin parameter may be set by which request deadlines must be met. Also, an available rate parameter may be set to proportion available bandwidth between rate-guaranteed streams and non-rate-guaranteed requests. The proportion allocated for rate-guaranteed requests may be used to determine buffer sizes that are able to meet the prefill margin. Another parameter may set the length of a seek reorder queue that orders storage requests according to their physical address. This parameter allows a tradeoff between seek efficiency and variability in service time, which may require larger buffer sizes. Also, the block size by which data is accessed in the storage system may be configured.