Netapp, Inc.

Sethuraman Subbiah

David Slik

Gokul Soundararajan

Lakshmi Narayanan Bairavasundaram

Keith Arnold Smith

Atish Kathpal

Giridhar Appaji Nag Yasa

Shehbaz Jaffer

Tanya Shastri

A rebuild node of a storage system can assess risk of the storage system not being able to provide a data object. The rebuild node(s) uses information about data object fragments to determine health of a data object, which relates to the risk assessment. The rebuild node obtains object fragment information from nodes throughout the storage system. With the object fragment information, the rebuild node(s) can assess object risk based, at least in part, on the object fragments indicated as existing by the nodes. To assess object risk, the rebuild node(s) treats absent object fragments (i.e., those for which an indication was not received) as lost. When too many object fragments are lost, an object cannot be rebuilt. The erasure coding technique dictates the threshold number of fragments for rebuilding an object. The risk assessment per object influences rebuild of the objects.

Risk based rebuild of data objects in an erasure coded storage system

A dynamic caching technique adaptively controls copies of data blocks stored within caches ('cached copies') of a caching layer distributed among servers of a distributed data processing system. A cache coordinator of the distributed system implements the dynamic caching technique to increase the cached copies of the data blocks to improve processing performance of the servers. Alternatively, the technique may decrease the cached copies to reduce storage capacity of the servers. The technique may increase the cached copies when it detects local and/or remote cache bottleneck conditions at the servers, a data popularity condition at the servers, or a shared storage bottleneck condition at the storage system. Otherwise, the technique may decrease the cached copies at the servers.

Dynamic caching technique for adaptively controlling data block copies in a distributed data processing system

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San Jose, CA, United States of America

Sethuraman Subbiah