Users may also want to retry for a certain period of time before proceeding

Users may also want to retry for a certain period of

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policy by default but you can also set it to a fixed policy. Users may also want to retry for a certain period of time before proceeding with the rest of their job without throwing an exception. They can achieve this by setting fs.s3.consistent.throwExceptionOnInconsistency to false , fs.s3.consistent.retryPolicyType to fixed , and fs.s3.consistent.retryPeriodSeconds for the desired value. The following example creates a cluster with consistency enabled, which logs inconsistencies and sets a fixed retry interval of 10 seconds: Example Setting retry period to a fixed amount aws emr create-cluster --release-label emr-5.28.1 \ --instance-type m5.xlarge --instance-count 1 \ --emrfs Consistent= true ,Args=[fs.s3.consistent.throwExceptionOnInconsistency= false , fs.s3.consistent.retryPolicyType= fixed ,fs.s3.consistent.retryPeriodSeconds= 10 ] --ec2- attributes KeyName= myKey Note Linux line continuation characters (\) are included for readability. They can be removed or used in Linux commands. For Windows, remove them or replace with a caret (^). For more information, see Consistent View (p. 63) . EMRFS Consistent View Metadata EMRFS consistent view tracks consistency using a DynamoDB table to track objects in Amazon S3 that have been synced with or created by EMRFS. The metadata is used to track all operations (read, write, update, and copy), and no actual content is stored in it. This metadata is used to validate whether the objects or metadata received from Amazon S3 matches what is expected. This confirmation gives EMRFS the ability to check list consistency and read-after-write consistency for new objects EMRFS writes to Amazon S3 or objects synced with EMRFS. Multiple clusters can share the same metadata. How to add entries to metadata You can use the sync or import subcommands to add entries to metadata. sync reflects the state of the Amazon S3 objects in a path, while import is used strictly to add new entries to the metadata. For more information, see EMRFS CLI Reference (p. 72) . 66
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Amazon EMR Management Guide Consistent View How to check differences between metadata and objects in Amazon S3 To check for differences between the metadata and Amazon S3, use the diff subcommand of the EMRFS CLI. For more information, see EMRFS CLI Reference (p. 72) . How to know if metadata operations are being throttled EMRFS sets default throughput capacity limits on the metadata for its read and write operations at 400 and 100 units, respectively. Large numbers of objects or buckets may cause operations to exceed this capacity, at which point they are throttled by DynamoDB. For example, an application may cause EMRFS to throw a ProvisionedThroughputExceededException if you are performing an operation that exceeds these capacity limits. Upon throttling, the EMRFS CLI tool attempts to retry writing to the DynamoDB table using exponential backoff until the operation finishes or when it reaches the maximum retry value for writing objects from Amazon EMR to Amazon S3.
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  • Spring '12
  • LauraParker
  • Amazon Web Services, Amazon Elastic Compute Cloud

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