Google Inc.

Steven Robert Schirripa

Robert Cypher

Sean Quinlan

Christian Eric Schrock

Lidor Carmi

Peter Dahl

Healfdene Goguen

A method of distributing data in a distributed storage system includes receiving a file, dividing the received file into chunks, and determining a distribution of the chunks among storage devices of the distributed storage system based on a maintenance hierarchy of the distributed storage system. The maintenance hierarchy includes maintenance levels, and each maintenance level includes one or more maintenance units. Each maintenance unit has an active state and an inactive state. Moreover, each storage device is associated with a maintenance unit. The determining of the distribution of the chunks includes identifying a random selection of the storage devices matching a number of chunks of the file and being capable of maintaining accessibility of the file when one or more maintenance units are in an inactive state. The method also includes distributing the chunks to storage devices of the distributed storage system according to the determined distribution.

Distributing data on distributed storage systems

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 that prevents unnecessary data recovery includes receiving, at a data processing device, a status of a resource of a distributed system. When the status of the resource indicates a resource failure, the method includes executing instructions on the data processing device to determine whether the resource failure is correlated to any other resource failures within the distributed system. When the resource failure is correlated to other resource failures within the distributed system, the method includes delaying execution on the data processing device of a remedial action associated with the resource. However, when the resource failure is uncorrelated to other resource failures within the distributed system, the method includes initiating execution on the data processing device of the remedial action associated with the resource.

Preventing unnecessary data recovery

A method includes identifying high-availability jobs and low-availability jobs that demand usage of resources of a distributed system. The method includes determining a first quota of the resources available to low-availability jobs as a quantity of the resources available during normal operations, and determining a second quota of the resources available to high-availability jobs as a quantity of the resources available during normal operations minus a quantity of the resources lost due to a tolerated event. The method includes executing the jobs on the distributed system and constraining a total usage of the resources by both the high-availability jobs and the low-availability jobs to the quantity of the resources available during normal operations.

Efficient resource utilization in data centers

A method of prioritizing data for recovery in a distributed storage system includes, for each stripe of a file having chunks, determining whether the stripe comprises high-availability chunks or low-availability chunks and determining an effective redundancy value for each stripe. The effective redundancy value is based on the chunks and any system domains associated with the corresponding stripe. The distributed storage system has a system hierarchy including system domains. Chunks of a stripe associated with a system domain in an active state are accessible, whereas chunks of a stripe associated with a system domain in an inactive state are inaccessible. The method also includes reconstructing substantially immediately inaccessible, high-availability chunks having an effective redundancy value less than a threshold effective redundancy value and reconstructing the inaccessible low-availability and other inaccessible high-availability chunks, after a threshold period of time.

Prioritizing data reconstruction in distributed storage systems

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.

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 using a computer processor in communication with the non-transitory memory. The method also includes distributing chunks to storage devices of the distributed storage system based on a maintenance hierarchy of the distributed storage system. The maintenance hierarchy includes maintenance units each having active and inactive states. Moreover, each storage device is associated with a maintenance unit. The chunks are distributed across multiple maintenance units to maintain accessibility of the file when a maintenance unit is in an inactive state.

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Hazlet, NJ, United States of America

Steven Robert Schirripa