Google Inc.

Lidor Carmi

Steven Robert Schirripa

Christian Eric Schrock

Robert Cypher

Sean Quinlan

A method of operating a distributed storage system, the method includes identifying missing chunks of a file. The file is divided into stripes that include data chunks and non-data chunks. The method also includes identifying non-missing chunks available for reconstructing the missing chunks and reconstructing missing data chunks before reconstructing missing non-data chunks using the available non-missing chunks.

Data reconstruction in distributed storage systems

A method of operating a distributed storage system, the method includes identifying unhealthy chunks of a file. The file is divided into stripes that include data chunks and non-data chunks. The method also includes identifying healthy chunks available for reconstructing the unhealthy chunks and reconstructing unhealthy data chunks before reconstructing unhealthy non-data chunks using the available healthy chunks. When the unhealthy chunk is an unhealthy word-check chunk: reconstructing the unhealthy word-check chunk using healthy word-check chunks and healthy code-check-word-check chunks; determining whether reconstruction of the unhealthy word-check chunk is possible using only healthy word-check chunks and healthy code-check-word-check chunks; and when reconstruction of the unhealthy word-check chunk is not possible using only healthy word-check chunks and healthy code-check-word-check chunks, reconstructing the unhealthy word-check chunk using any healthy chunks.

A method of distributing data in a distributed storage system includes receiving a file and dividing the received file into chunks. The chunks are data-chunks and non-data chunks. The method further includes grouping chunks into a group and determining a distribution of the chunks of the group among storage devices of the distributed storage system based on a maintenance hierarchy of the distributed storage system. The maintenance hierarchy includes hierarchical maintenance levels and maintenance domains. Each maintenance domain has an active state or an inactive state; and each storage device is associated with at least one maintenance domain. The method also includes distributing the chunks of the group to the storage devices based on the determined distribution. The chunks of the group are distributed across multiple maintenance domains to maintain an ability to reconstruct chunks of the group when a maintenance domain is in the inactive state.

Efficient data reads from distributed storage systems

A method of distributing data in a distributed storage system includes receiving a file into non-transitory memory and dividing the received file into chunks. The chunks are data-chunks and non-data chunks. The method also includes grouping one or more of the data chunks and one or more of the non-data chunks in a group. One or more chunks of the group is capable of being reconstructed from other chunks of the group. The method also includes distributing the chunks of the group to storage devices of the distributed storage system based on a hierarchy of the distributed storage system. The hierarchy includes maintenance domains having active and inactive states, each storage device associated with a maintenance domain, the chunks of a group are distributed across multiple maintenance domains to maintain the ability to reconstruct chunks of the group when a maintenance domain is in an inactive state.

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Lidor Carmi