Details
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Bug
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Status: Open
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Major
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Resolution: Unresolved
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Description
HDFS currently detects corrupted replicas by verifying that its contents matches the checksum stored in the block meta-file. This is done independently for each replica of the block on the data-node it belongs to. But we do not check that the replicas are identical across data-nodes as long as they have the same size.
This is not common but can happen as a result of a software bug or an operator mismanagement. And in this case different clients will read different data from the same file.