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Tsz Wo Nicholas Sze commented on HDFS-7858: ------------------------------------------- Never mind. Thanks for the response. > Improve HA Namenode Failover detection on the client > ---------------------------------------------------- > > Key: HDFS-7858 > URL: https://issues.apache.org/jira/browse/HDFS-7858 > Project: Hadoop HDFS > Issue Type: Improvement > Components: hdfs-client > Reporter: Arun Suresh > Assignee: Arun Suresh > Labels: BB2015-05-TBR > Fix For: 2.8.0 > > Attachments: HDFS-7858.1.patch, HDFS-7858.10.patch, > HDFS-7858.10.patch, HDFS-7858.11.patch, HDFS-7858.12.patch, > HDFS-7858.13.patch, HDFS-7858.2.patch, HDFS-7858.2.patch, HDFS-7858.3.patch, > HDFS-7858.4.patch, HDFS-7858.5.patch, HDFS-7858.6.patch, HDFS-7858.7.patch, > HDFS-7858.8.patch, HDFS-7858.9.patch > > > In an HA deployment, Clients are configured with the hostnames of both the > Active and Standby Namenodes.Clients will first try one of the NNs > (non-deterministically) and if its a standby NN, then it will respond to the > client to retry the request on the other Namenode. > If the client happens to talks to the Standby first, and the standby is > undergoing some GC / is busy, then those clients might not get a response > soon enough to try the other NN. > Proposed Approach to solve this : > 1) Use hedged RPCs to simultaneously call multiple configured NNs to decide > which is the active Namenode. > 2) Subsequent calls, will invoke the previously successful NN. > 3) On failover of the currently active NN, the remaining NNs will be invoked > to decide which is the new active -- This message was sent by Atlassian JIRA (v6.3.4#6332)