Konstantin Shvachko created HDFS-6325:
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Summary: Append should fail if the last block has unsufficient
number of replicas
Key: HDFS-6325
URL: https://issues.apache.org/jira/browse/HDFS-6325
Project: Hadoop HDFS
Issue Type: Bug
Components: namenode
Affects Versions: 2.2.0
Reporter: Konstantin Shvachko
Fix For: 2.5.0
Currently append() succeeds on a file with the last block that has no replicas.
But the subsequent updatePipeline() fails as there are no replicas with the
exception "Unable to retrieve blocks locations for last block". This leaves the
file unclosed, and others can not do anything with it until its lease expires.
The solution is to check replicas of the last block on the NameNode and fail
during append() rather than during updatePipeline().
How many replicas should be present before NN allows to append? I see two
options:
# min-replication: allow append if the last block is minimally replicated (1 by
default)
# full-replication: allow append if the last block is fully replicated (3 by
default)
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