Western Digital Technologies, Inc.

James C Alexander

James N Malina

Kent Douglas Anderson

Robert L Horn

Albert H Chen

A data storage system includes a plurality of Data Storage Devices (DSDs). A write command is sent to each DSD of the plurality of DSDs to each store one or more erasure coded shards of an overprovisioned number of shards. The overprovisioned number of shards is generated from an erasure coding on data to provide at least a predetermined level of data reliability. Write complete indications are received for a threshold number of shards less than the overprovisioned number of shards, with each write complete indication indicating that one or more shards of the overprovisioned number of shards has been stored in a DSD. It is determined that the data has been written with at least the predetermined level of data reliability after receiving write complete indications for the threshold number of shards, but before receiving write complete indications for all of the overprovisioned number of shards.

Write latency reduction

A collective latency indicator is determined that is associated with a latency in retrieving multiple erasure coded shards generated from an erasure coding on initial data. The collective latency indicator is compared to a latency limit, and a number of erasure coded shards to retrieve is adjusted based on the comparison of the collective latency indicator to the latency limit.

Read tail latency reduction

An individual latency indicator is determined for each Data Storage Device (DSD) or memory portion of a DSD storing one or more erasure coded shards generated from an erasure coding on initial data. Each individual latency indicator is associated with a latency in retrieving an erasure coded shard stored in a respective DSD or memory portion. At least one collective latency indicator is determined using determined individual latency indicators, with the at least one collective latency indicator being associated with a latency in retrieving multiple erasure coded shards. The at least one collective latency indicator is compared to a latency limit, and a subset of erasure coded shards is selected to retrieve based on the comparison of the at least one collective latency indicator to the latency limit.

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Newport Coast, CA, United States of America

James C Alexander