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Steve Loughran commented on HADOOP-7550: ---------------------------------------- One other complication is that Facebook negotiate RPC versions; adding a checksum on top would break this. Could we target the low-level encodings like thrift and/or protocol buffers, and do it at what is effectively the transport layer? > Need for Integrity Validation of RPC > ------------------------------------ > > Key: HADOOP-7550 > URL: https://issues.apache.org/jira/browse/HADOOP-7550 > Project: Hadoop Common > Issue Type: Improvement > Components: ipc > Reporter: Dave Thompson > Assignee: Dave Thompson > > Some recent investigation of network packet corruption has shown a need for > hadoop RPC integrity validation beyond assurances already provided by 802.3 > link layer and TCP 16-bit CRC. > During an unusual occurrence on a 4k node cluster, we've seen as high as 4 > TCP anomalies per second on a single node, sustained over an hour (14k per > hour). A TCP anomaly would be an escaped link layer packet that resulted > in a TCP CRC failure, TCP packet out of sequence > or TCP packet size error. > According to this paper[*]: http://tinyurl.com/3aue72r > TCP's 16-bit CRC has an effective detection rate of 2^10. 1 in 1024 errors > may escape detection, and in fact what originally alerted us to this issue > was seeing failures due to bit-errors in hadoop traffic. Extrapolating from > that paper, one might expect 14 escaped packet errors per hour for that > single node of a 4k cluster. While the above error rate > was unusually high due to a broadband aggregate switch issue, hadoop not > having an integrity check on RPC makes it problematic to discover, and limit > any potential data damage due to > acting on a corrupt RPC message. > ------ > [*] In case this jira outlives that tinyurl, the IEEE paper cited is: > "Performance of Checksums and CRCs over Real Data" by Jonathan Stone, Michael > Greenwald, Craig Partridge, Jim Hughes. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira